Helping wild animals through vaccination: could this happen for coronaviruses like SARS-CoV-2?
Cross-posted from the Animal Ethics blog.
Wild animals can suffer and die prematurely due to many factors, including harmful weather conditions, hunger, thirst and malnutrition, parasitism, conflicts, and accidents. One of these factors, which painfully kills vast numbers of animals, is disease.
Fortunately for many animals, however, wild animal vaccination programs have been conducted for decades already. For the most part, they have been implemented to prevent zoonotic diseases from spreading from nonhuman animals to humans (or to other animals humans live with). But, regardless of this, such programs have prevented huge amounts of suffering and saved the lives of many wild animals. Thorough vaccination efforts can even eradicate a disease by drastically reducing the transmission rate. For example, as we will see below, rabies has been eliminated from large areas of North America and Europe. These successes show that it would be feasible to implement similar programs out of a concern for animals themselves. Scientists have shown support for gaining more knowledge about this method of helping animals in the wild.
The extent to which some animals can suffer from different diseases has become prominent due to the present COVID-19 pandemic. Many people now know that close contact between animals, including humans, provides opportunities for zoonoses, that is, for diseases to jump between species. The elimination of disease reservoirs, such as these among animal populations, has typically motivated wild animal vaccination programs.
A question that can therefore arise is whether it might eventually be possible to vaccinate animals who are threatened by coronaviruses like SARS-CoV-2, the cause of COVID-19. It seems that if a vaccine were successfully developed, there would be an incentive to do so, even for those caring only about human health and not about animals, because this measure could prevent eventual zoonotic infections. But, as with other vaccination programs, many nonhuman animals would be substantially helped by such a measure.
Below we will examine this question in more detail. We will first see some cases of successful vaccination programs in the past, including vaccination against rabies, anthrax, rinderpest, brucellosis, and sylvatic plague, in addition to the proposal to vaccinate great apes against Ebola. Next, we will see how zoonotic epidemics have been the object of growing attention.We will then see some responses to them that are misguided and harmful to animals. We will then see the prospects for eventual wild animal vaccination programs against coronaviruses like SARS-CoV-2. We will see the three main limitations of such hypothetical programs. These are the lack of an effective vaccine, the lack of funding to implement the vaccination program, and the lack of an effective system to administer the vaccine. We’ll consider the extent to which these limitations could be overcome and what clues previous examples of vaccination can provide. As we will see, such programs remains to date merely speculative. They could be feasible at some point as other wild animal vaccination programs show. However, it remains uncertain whether there will be human interest in implementing them, despite the benefits for animals themselves.
Finally, we will see the reasons why, if implemented, programs of this kind could substantially help not just the vaccinated animals, but many others as well. Not only would this prevent zoonotic disease transmission to other animals, but such measures could also help inform other efforts to vaccinate animals living in the wild. Moreover, each successful vaccination program helps to illustrate that helping animals in the wild is not impractical, but realistic. This helps to raise concern for these animals and to inspire action on their behalf.
Examples of vaccination programs
Many people don’t realize how extensively animals living in the wild have already been vaccinated. Of course, this has happened for only a tiny minority of the huge number of diseases that we could vaccinate them for. However, the vaccinations have still had a very big impact for large numbers of animals. Below are some examples (more information is found on our page that gives an overview of wild animal vaccinations).
Vaccination against rabies is probably the best example of wild animal vaccination, because it is the one that has been carried out most extensively, and for several decades already. Rabies causes great suffering and almost certain death in the victims it infects (regardless of whether they are human or nonhuman animals). Some potential symptoms are fever, pain, tingling/burning sensations, hydrophobia, aggression, confusion, and muscle paralysis. Vaccination for rabies has been implemented effectively through means such as the dispersal of oral baits containing the vaccine from helicopters. By this method, it has already been mostly eliminated in large areas in Europe and North America.
In the U.S., attempts to reduce the spread of rabies began in the 1970s. It has been estimated that one of these programs vaccinated close to two-thirds of the population of raccoons in Massachusetts. Another program vaccinated coyotes in Texas and led to a large reduction in the number of new cases. It has been suggested that with the coordinated efforts of the USA, Canada, and Mexico it would be feasible to achieve the complete elimination rabies in many other parts of North America.
Anthrax is spread by the bacterium Bacillus anthracis. The bacteria release spores that can cause infections when they are inhaled, ingested, or pass through an open wound. The spores are incredibly resilient and can remain infectious for years in the soil or in the body of an animal. Herbivorous animals may ingest spores while grazing and predatory animals may ingest spores through the bodies of herbivorous animals.
Once infected, symptoms can include high fever, muscle tremors, and difficulty in breathing. Outbreaks can lead to immense suffering and death among animals. Among herbivorous mammals, outbreaks can kill between 21% and 51% of hippos and up to 90% of impalas and kudos. A 2016 outbreak in Siberia killed 2,300 reindeers.
Fortunately, in some cases, Guinea pigs, zebras, and rhinos have all successfully been vaccinated against anthrax. In one outbreak in Eastern Africa, 53 zebras died from anthrax. The remaining 650 zebras were all vaccinated and there were no further deaths.
Rinderpest vaccination is an example of a great success story in the vaccination of animals. Rinderpest was an infectious viral disease that harmed cows, bisons, wildebeests, giraffes, antelopes, warthogs, and other even-toed ungulates. Symptoms included fever, loss of appetite, discharge from the nose and eyes, constipation followed by acute diarrhea, and lesions in the mouth, the lining of the nose, and the genital tract. Death would typically follow in 6 to 12 days. In previously unexposed populations, the mortality rate was close to 100%. An outbreak in the 1890s killed around 90% of the cows in southern and eastern Africa, as well as many other animals.
Because animals exploited by people were greatly harmed by the disease, action was taken in this case that would likely not have been otherwise. A huge number of domesticated animals were vaccinated against the disease.
In June 2011, the World Organisation for Animal Health officially announced that the disease had been eradicated globally. Though animals living in the wild were not vaccinated, the disease was still eradicated, which continues to protect them from very severe harms. The benefit to wild animals was not intentional, but it was still greatly beneficial to them. As an example of this, consider that the population of wildebeests on the Serengeti in 1957 was 100,000. In 1971, just 10 years after the first vaccine was developed, the population had grown to 770,000. This shows the huge amount of suffering and death that the disease must have been causing these animals.
Brucellosis is a contagious disease spread by different bacteria in the Brucella family. It primarily damages the reproductive system, leading to stillbirths, birth defects, and other birthing complications. It can cause swelling of the testicles in males. It can also affect the joints, causing arthritis.
An estimated 12.5 thousand elks and 2.5 thousand bisons within Yellowstone National Park are infected. To combat the disease in this area, a vaccine has been developed for the bisons in that area. Vaccinating bisons in this area is being now discussed, and this measure would probably improve their welfare and prevent their spreading the diseases to other animals.
Sylvatic plague is an infectious bacterial disease caused by the bacterium Yersina pestis. This is the same bacterium that is responsible for the bubonic plague in humans. It causes outbreaks in animals such as ferrets and prairie dogs.
Symptoms can include fever, dehydration, low energy, lack of appetite, difficulty breathing, enlarged spleen, and swollen lymph nodes. The disease is usually fatal in prairie dogs.
Out of conservationist concern for ferrets, who were dying because they attack and eat prairie dogs, vaccination programs were adopted. Once prairie dogs are vaccinated, their survival rate improves to 95%. Vaccination is done through oral baits rather than hypodermic darts, which makes the process faster and less intrusive to the prairie dogs.
Since the 1990s, the Zaire strain of Ebola has killed approximately one third of the populations of both gorillas and chimpanzees. Ebola is a horrifying disease that can cause fever, internal bleeding, muscle weakness, difficulty breathing and swallowing, vomiting, and diarrhea. In gorillas, the mortality rate may be as high as 90%. Vaccinating apes against Ebola is another area where action has been suggested. This could be done through either an oral bait or a hypodermic dart.
As large animals that are similar to humans in many ways, nonhuman Great Apes like gorillas and chimpanzees tend to be much more respected by humans and treated better than other animals. It is likely that these proposals are taken more seriously for this reason and also because of the risk of Ebola spreading from them to humans, even though other animals deserve the same concern.
Growing concerns about zoonotic epidemics for reasons focused on human interests
Interest in wild animal vaccination has grown in recent decades, moved mainly by concerns about the health of humans, rather than that of other animals. This has been due to the risk of zoonotic epidemics, as it is currently estimated that around three of four new pathogens infecting humans may be spread to humans through animals, and this figure has increased over time.
We are now witnessing an example of this, as evidence strongly indicates that the COVID-19 pandemic stems from a horseshoe bat betacoronavirus which made the jump to humans, probably through an intermediate host such as pangolins  (though SARS-CoV-2-like viruses have also been found in civets and raccoon dogs).
The SARS (severe acute respiratory syndrome) outbreak in humans in 2003 was caused by a different betacoronavirus that, it is believed, spread from bats to civets and then from civets to humans. Nine years later, in 2012, the MERS (Middle East respiratory syndrome) outbreak was caused by betacoronavirus MERS-CoV, which is suspected to have originated in bats and to have spread from bats to camels 20 years earlier and then from camels to humans. There may have been other cases of disease outbreaks spread by bats to nonhuman animals. The origin of the other four coronaviruses known to affect humans with milder effects (betacoronaviruses HCoV-OC43 and HCoV-HKU1, and alphacoronaviruses HCoV-229E and HCoV-NL63) is also likely to be zoonotic.
Wet markets, which bring many different animals together in appalling conditions, are thought to be responsible for facilitating the jump between species of the two SARS-CoV viruses (2003 and 2019) in China. This has led to western criticisms of China due to the consequences this has for human health and, to a lesser extent, because of the ways animals are exploited there. Inflicting harms on animals for human benefit is also the norm in the rest of the world. In addition, western factory farms similarly pose a great risk of viral outbreaks to humans, with previous records including different H1N1 pandemics and several other types of influenza, in addition to the growing risk of pandemics of bacterial diseases due to bacterial resistance to the antibiotics used in current farming. (In fact, the World Health Organization has been warning of the risk of pandemics for a long time, although it was considered more likely that the next pandemic would be a flu that originated in a farm.)
From a point of view that takes into account all sentient beings, these considerations aren’t needed in order to oppose animal exploitation. Nonhuman animals are sentient beings who, like humans, are harmed when they are made to suffer and die. The reason we give moral consideration to someone should not be the species to which they belong, or whether they have certain intellectual capacities, but whether they can feel and suffer. This means that it should be unacceptable to exploit animals, as we routinely do, in factory farms and wet markets, as well as in other farms and businesses. Accordingly, harms or threats to human health are unnecessary in order to oppose these forms of exploitation. This applies equally to China, western countries, and the rest of the world.
Attitudes of disregard for nonhuman animals have terrible consequences for those who are made to suffer and die in farms and markets. It also tends to be accompanied by a disregard for what happens to animals in the wild. This can be seen in how interest in zoonotic diseases is based mostly on human health alone. As a result, virus outbreaks that affect nonhuman animals but not humans have not been as well studied and have not entered the public consciousness, particularly those that affect animals who live in the wild. It’s reasonable to suppose that there have been many cases of viruses spread from bats to other kinds of nonhuman animals which have caused huge amounts of suffering to those animals. We can see at least a few cases of this from the outbreaks in the intermediate hosts of COVID-19, SARS, and MERS. The majority of coronaviruses affecting nonhuman animals are studied very little. Among the best known coronaviruses are some that affect animals used by humans, such as IBV (Avian infectious bronchitis virus), PorCoV HKU15 (Porcine coronavirus HKU15), PEDV (Porcine epidemic diarrhea virus), RECV (Rabbit enteric coronavirus), CCoV (Canine coronavirus) and FCoV (Feline coronavirus), although others affecting animals in the wild have also been identified, especially among bats, as well as in some other animals ranging from birds to hedgehogs.
Reactions to zoonoses resulting from animal exploitation
Unfortunately, wild animals have in many cases been killed to reduce disease transmission to humans and to animals who humans exploit for various reasons. Mass slaughters of animals such as chickens, hens, pigs, geese and others during disease outbreaks originating in farms have become a standard procedure. Something similar is sometimes done to wild animals. Following the 2003 SARS outbreak in humans, the Chinese government ordered the slaughter of 10,000 civets seized in markets, against WHO indications. Right now, bats have been slaughtered in various places throughout the world due to the belief that this may help to prevent the spread of COVID-19. Professor of Zoology at Wuhan University, Huabin Zhao, has pointed out that locals are expelling hibernating bats in the city, capturing and releasing them in the wild (where they may not survive, because they are used to living in the city), as well as supporting killing them. The belief that all kinds of bat species, not just horseshoe bats — who don’t hibernate in cities like Wuhan — can spread COVID-19 to you if they pass close to you is present in many other countries too (from Indonesia to Peru to the USA). Some even have the view that bats are somehow to blame for the pandemic, instead of humans who have caused it through their consumption of animal products.
Even if bats could pass the disease to human beings, killing them would not only be objectionable from a position that defends the moral consideration of all sentient beings; it also wouldn’t work to prevent zoonotic infections. An example of this is provided, again, by the case of rabies, which as we have seen can indeed be passed to humans by certain animals, including bats. We have seen already that vaccination can work to stop the spread of this disease. In contrast, it is currently understood that killing them does not work. This is because killing bats only reduces their population. It cannot eliminate the disease. But bats from colonies that are attacked will flee to other colonies. This can infect new colonies with rabies who can in turn infect other animals. In this way, killing bats can actually help to spread the disease faster.  Educating the public and in some cases policy makers about all this is necessary in order to avoid misguided reactions that harm animals.
There are actions that are beneficial for animals and that are also effective in protecting humans against zoonoses. These include not using animals as resources for food and other purposes and actively engaging in helping animal populations to fight the diseases they suffer from. The first one, which would imply that humans would stop harming them, has been pointed out already by others. Our concern here is with the second one.
Could wild animals be vaccinated against coronaviruses at some point?
In the first section of this paper we saw how, despite disregard for animals, it has been increasingly considered that vaccinating animals is more effective in reducing disease transmission than killing those animals. The connection between the health of humans and other animals has led to action being taken in many cases that protect the health of wild animals, resulting in substantial benefits for these animals.
Three apparent limitations to the feasibility of a measure like this are:
(i) the lack of an effective vaccine,
(ii) the lack of funding to implement the vaccination programs, and
(iii) the lack of an effective method to administer the vaccine
In the following section, we will consider how these liminations apply to vaccination against coronaviruses likes SARS-CoV-2.
The lack of vaccines
Of all these limitations, the one that may seem most salient right now is the first one. To start with, programs of this kind would only be implemented after a vaccine is developed and distributed among human beings. This means the timing for this is uncertain. . There is still no vaccine for SARS. Once the SARS epidemic was controlled more than 15 years ago, funding for efforts to develop a vaccine against them saw a dramatic decline. There is no vaccine for MERS available yet either, for similar reasons. On the other hand, substantial efforts are now being undertaken to find a human vaccine for COVID-19. If a vaccine were developed early this decade, it would be feasible for vaccines for animals to follow, and a wild animal vaccination program could be implemented at some point in the 2020s.
As we have seen above, research is being done to identify and learn more about other coronaviruses affecting animals. It seems that, given the visibility the viruses have now have gained because of their zoonotic potential, such research will increase and more knowledge will be gained about them this decade. However, there is a long way from this to the actual development of vaccines against them, and it doesn’t seem realistic to expect that a lot of resources will be spent on this in the short term. Decision makers in different countries have a track record of taking care of zoonotic threats almost exclusively when the health or economic risks to humans are very clearly recognizable and immediate. They will probably priotitize other things in the coming years of economic crisis.
It is still possible that this might change at some future point, even in the absence of a concern for the animals, as more knowledge is gathered about potentially zoonotic coronaviruses affecting animals with whom humans interact, and as a result of fears of a new coronavirus-caused pandemic.
Funding constraints to implementing vaccination programs
Just as we have seen that funding can be the bottleneck for vaccines against different coronaviruses being developed, it can also determine whether wild animal vaccination programs are ever implemented or not. As mentioned above, because the interests of nonhuman animals are typically disregarded, so it is likely that action will be taken only when a clear connection with human interests is perceived. Yet previously successful wild animal vaccination programs show that when those interests are present, funding has been readily provided, even when the programs are ambitious ones.
It is therefore likely that in the coming years, funding for vaccinating nonhuman animals against coronaviruses would be available only if the existence of reservoirs for a serious disease threatening humans like COVID-19 were identified in animal populations. As for coronaviruses other than the ones already present in human populations, it seems that, as pointed out above, preventive measures targeting nonhuman animals are not likely to take place in the short term or maybe even in the mid term, although it is not unreasonable to think that this might change in the future.
Among the three limitations listed above, feasibility may represent less of a technical challenge than the other two. In animals like civets and raccoon dogs, methods like the ones used for rabies vaccination could be applied for vaccinations against other viruses. Something similar could take place for other large or medium-sized mammals. It seems that there wouldn’t be a major technical obstacle to vaccinating them against coronaviruses, and this could happen if they are found to be carrying viruses that might harm humans.
Bat vaccination programs face complications that are not present with other mammals, but they are not unsolvable ones. Some species may eat baits with the vaccine in them, but others will not. To get some hints about how this problem could be approached, we will see experiences with vaccinating bats against other diseases (although these experiences can only tell us the situation at this point, because this is a field that may see further developments in forthcoming years).
White nose disease
White nose disease is makes an interesting comparison because it infects bats in huge numbers, although it is a fungal infection rather than a virus. It is caused by the fungus Pseudogymnoascus destructans, and it harms bats by disrupting their hibernation, causing them to wake up and waste critical energy reserves. It normally causes an appalling 90% mortality rate in some species, but with administration of probiotics this rate is roughly halved. The fungus is thought to have killed more than 6 million bats in North America. The probiotic can be administered through a mist.
Though vaccines against fungal infections are rare, researchers have recently proposed developing a vaccine against Pseudogymnoascus destructans and vaccinating bats in North America against it. The method of deploying it cannot be individualized, but in a liquid, gel or spray that can be administered en masse to bats. These dispersal methods have already been studied for other cases in this research, and it seems reasonable to guess that the research may also be applicable to other vaccination programs.
Rabies (in bats)
There have been a number of studies on vaccinating bats against rabies and effective vaccines have been found. The goal of these studies and proposals to vaccinate vampire bats against rabies is to reduce the spread of rabies from vampire bats to humans and cows (because of their economic value to humans through their exploitation). It has not yet been done on a large scale outside of these trials, though research favors doing it because of its cost effectiveness, even from a speciesist perspective alone. Other kinds of bats can also be vaccinated.
Similar to what is done to combat white nose disease, scientists have developed a gel rabies vaccine that can be spread between bats when they make contact with each other. The bats will later lick the gel when they groom themselves. In this way, for each bat they apply the gel to, a total of 2.6 bats on average are protected. This seems like a promising application method that can be used in the future and it seems reasonable that it could be used to distribute coronavirus vaccines in bats.
In light of all this, it seems that the main issue when it comes to whether animals might be vaccinated against coronaviruses are not technical impediments or the eventual development of a vaccine, but rather whether the presence of such viruses in animal populations would be considered a relevant enough threat to human health and economic interests. If it is done, it would be very beneficial to the animals affected, as well as to many others, as we will see next.
How every wild animal vaccination program can be beneficial to other animals too
Zoonoses spreading from nonhuman animals to humans are a minority of those occurring: most occur between different species of nonhuman animals. This is why, as mentioned above in the case of bats, vaccinating certain animals can help not only animals of those populations, but also many other nonhuman animals to whom they could have passed the disease. This may be the case especially for bats, because they have one of the highest disease burdens among wild mammals. Among other conditions, they are harmed by a number of different coronaviruses-caused diseases. In fact, they harbor more than half of all known coronaviruses. Some factors that may contribute to this high disease burden are that they have high genetic diversity (there are both many species and many individual bats), they’re long-lived, and they roost in large groups. Moreover, bats have strong immune systems, which means that viruses that infect them need to be virulent. This, in turn, means they tend to be more harmful to other animals that the diseases jump to than they are to bats. Coronaviruses, in particular, have a high rate of recombination and mutation which makes it more likely for them to infect new kinds of animals. In addition, because bats fly, they can spread diseases over a wider area. This makes the continued presence of coronaviruses and of other viruses in bats dangerous to other animals as well.There is another important benefit when any new vaccination program takes place: we gain more information about how to conduct future vaccination programs that can help animals. For this reason, each new wild animal vaccination program can be very useful for more comprehensive work in the future.
In addition, these programs can help increase concern for sentient animals in general, which will be crucial not just in the short term, but especially in the long term, to improve their situation. To start with, showing the public an alternative to slaughter which works better and helps animals rather than harming them can make it easier to increase concern for them. This is similar to what happens when the availability of alternatives to animal exploitation leads to fewer people giving support to animal exploitation and more support to giving moral consideration to its victims.
What is more important, as mentioned above, animals in the wild suffer due to many different factors. Concern for them has already caused people in different places to get involved in different ways of helping them. These efforts have been able to help only a tiny portion of those who need help. But they have nevertheless succeeded in making this a more visible issue. These vivid examples also help counter the claim that, difficult as the situation is for these animals, there is no way we can change it. We should instead encourage further efforts to help animals more.
This is an even greater concern because in the future our ability to help animals in the wild may grow substantially. Due to this, it is critical that we raise concern for animals so that action will be taken when it can be. Successful wild animal vaccination programs, even when they are done out of a human interest, help show that it would be feasible to do them out of concern for nonhuman animals themselves. This can also generate more confidence in other initiatives to help wild animals, such as, for example, rescue programs for animals who are the victims of extreme weather events, or initiatives to improve the lives of animals in urban, suburban, and agricultural areas.
Finally, vaccination programs also challenge other objections to helping wild animals. Some people reject helping animals who live in the wild because they think that we should leave them alone, even when this means leaving them to suffer and die, for example due to some painful disease. In contrast, few people object to vaccination programs such as the ones we have seen above that also have beneficial effects for humans. This represents a double standard where it is acceptable to intervene for human interests but not for those of other animals. It shows a speciesist attitude which appears to underly this objection to helping animals who live in the wild. Also, seeing the feasibility of ways to help can increase support for them.
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 Vijgen, L.; Keyaerts, E.; Moës, E.; Thoelen, I.; Wollants, E.; Lemey, P.; Vandamme, A. M. & Van Ranst, M. (2005) “Complete genomic sequence of human coronavirus OC43: Molecular clock analysis suggests a relatively recent zoonotic coronavirus transmission event”, Journal of Virology, 79, pp. 1595-1604 [accessed on 4 May 2020].; Huynh, J.; Li, S.; Yount, B.; Smith, A.; Sturges, L.; Olsen, J. C.; Nagel, J.; Johnson, J. B.; Agnihothram, S.; Gates, J. E. & Frieman, M. B. (2012) “Evidence supporting a zoonotic origin of human coronavirus strain NL63”, Journal of Virology, 86, pp. 12816-12825; Ying T.; Mang S.; Chommanard, C.; Queen, K.; Jing Z.; Markotter, W.; Kuzmin, I. V.; Holmes, E. C. Suxiang T. (2017) “Surveillance of bat coronaviruses in Kenya identifies relatives of human coronaviruses NL63 and 229E and their recombination history”, Journal of Virology, 91, e01953-16 [accessed on 2 May 2020]; Zi-Wei Y.; Shuofeng Y.; Kit-San Y.; Sin-Yee F.; Chi-Ping C. & Dong-Yan J. (2020) “Zoonotic origins of human coronaviruses”, International Journal of Biological Sciences, 16, pp. 1686-1697 [accessed on 4 May 2020].
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 World Health Organization (2019) Global influenza strategy 2019-2030, World Health Organization, p. 4 [accessed on 2 May 2020]. See also Morse, S. S.; Mazet, J. A.; Woolhouse, M.; Parrish, C. R.; Carroll, D.; Karesh, W. B.; Zambrana-Torrelio, C.; Lipkin, W. I. & Daszak, P. (2012) “Prediction and prevention of the next pandemic zoonosis”, The Lancet, 380, pp. 1956-1965 [accessed on 2 May 2020].
 The harms caused by other coronaviruses to animals living in the wild is unfortunately not well known.There are many coronaviruses infecting many different kinds of animals, so the symptoms vary quite a lot. We do know that in mammals and birds they cause a variety of symptoms in primarily the respiratory system and gastrointestinal system, but can also affect the liver and the nervous system. See Bande, F.; Arshad, S. S.; Bejo, M. H.; Moeini, H. & Omar, A. R. (2015) “Progress and challenges toward the development of vaccines against avian infectious bronchitis”, Journal of Immunology Research, a424860 [accessed on 3 May 2020]; Brook, C. E. & Dobson, A. P. (2015) “Bats as ‘special’ reservoirs for emerging zoonotic pathogens”, Trends in Microbiology, 23, pp. 172-180 [accessed on 4 May 2020].
 Another example of these measures involving bats has been the slaughters of fruit bats, which is questioned in Olival, K. J. (2016) “To cull, or not to cull, bat is the question”, EcoHealth, 13, pp. 6-8 [accessed on 4 May 2020].
 CBS Interactive (2004) “Civet cat slaughter to fight SARS”, CBS News, 11 January [accessed on 16 April 2020].
 Huabin Z. (2020) “COVID-19 drives new threat to bats in China”, Science, 367, p. 1436 [accessed on 2 May 2020].
 South China Morning Post (2020) “Hundreds of bats culled in Indonesia to ‘prevent spread’ of the coronavirus”, South China Morning Post, YouTube, 16 March [accessed on 2 May 2020]; Phys.org (2020) “Peru saves bats blamed for coronavirus”, Biology, Phys.org, March 25 [accessed on 4 May 2020]; Morris, J. (2020) “Should we be worried about bats in San Jose making us sick?”, Mercury News, 14 February [accessed on 3 May 2020].
 Erickson-Michigan, J. (2013) “Culling vampire bats may spread rabies faster”, Futurity, 3 December [accessed on April 28 2020].
 Alagona, P. (2020) “It’s wrong to blame bats for the coronavirus epidemic”, The Conversation, 24 March [accessed on 4 May 2020]; Dalton, J. (2020) “Coronavirus: Exterminating bats blamed for spreading Covid-19 would increase risk of further diseases, warn experts”, The Independent, 19 April [accessed on 2 May 2020]; Ghosh, S. (2020) “Bats not the enemy in the fight against COVID-19”, Mongabay, 24 April [accessed on 1 May 2020].
 See for example Singer, P. & Cavalieri, P. (2020) “The two dark sides of COVID-19”, Project Syndicate, 2 March [accessed on 4 May 2020].
 Aubert, M. F. A. (1999) “Costs and benefits of rabies control inwildlife in France”, Revue scientifique et technique (International Office of Epizootics), 18, pp. 533-543; Blancou, J.; Pastoret, P. P.; Brochier, B.; Thomas, I. & Bögel, K. (1988) “Vaccinating wild animals against rabies”, Reviews in Science Technology, 7, pp. 1005-1013 [accessed on 7 May 2020].
 Ideally, we can speculate that one way to prevent potential pandemics caused by other viruses that still do not affect humans would consist in studying them and developing vaccines for them before they pass to humans, although it would be unrealistic to expect something like this will happen in the next years.
 Biao K.; Ming W.; Huaiqi J.; Huifang X.; Xiugao J.; Meiying Y.; Weili L.; Han Z.; Kanglin W.; Qiyong L.; Buyun C.; Yanmei X.; Enmin Z.; Hongxia W.; Jingrong Y.; Guichang L.; Machao L.; Zhigang C.; Xiaobao Q.; Kai C.; Lin D.; Kai G.; Yu-teng Z.; Xiao-zhong Z.; Yue-Ju F.; Yu-Fan G.; Rong H.; Dongzhen Y.; Yi G. & Jianguo X. (2005) op. cit.
 Hoyt, J. R.; Langwig, K. E.; White, J. P.; Kaarakka, H. M.; Redell, J. A.; Parise, K. L.; Frick, W. F.; Foster, J. T. & Kilpatrick, A. M. (2019) “Field trial of a probiotic bacteria to protect bats from white-nose syndrome”, Scientific Reports, 9 [accessed on 2 May 2020].
 O’Neill, K. (2019) “Spraying bats with ‘good’ bacteria may combat deadly white nose syndrome”, Science News, July 15 [accessed on 2 May 2020].
 Cushman, W. (2019) “The scientific frontier of vaccinating bats against a deadly virus”, WisContext, Nov. 8 [accessed on 16 April 2020].
 O’Neill, K. (2019) op. cit.
 Garner, S. (2018) “How to vaccinate a wild bat”, Scientific American, November 22 [accessed on 1 May 2020].
 These studies have focused on vaccinating vampire bats (which represent only three species of the 1200 species of bats in the world and live only in Latin America). Erickson-Michigan, J. (2013) “Culling vampire bats may spread rabies faster”, Futurity, December 3rd [accessed on 2 May 2020].
 Aguilar Sétien, A.; Brochier, B.; Tordo, N.; de Paz, O.; Desmettre, P.; Péharpré, D. & Pastoret, P.-P. (1998) “Experimental rabies infection and oral vaccination in vampire bats (Desmodus rotundus)”, Vaccine, 16, pp. 1122-1126.
 Lollar, A. (2004) “Vaccinating insectivorous bats against rabies”, International Bat Rehabilitation Journal, 2 (1), p. 1. The world bat sanctuary has been vaccinating all the bats there against rabies since 1990
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 Ben H.; Xingyi G.; Lin-Fa W. & Zhengli S. (2015) op. cit.
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