A new pre-print article from the Institut Pasteur in France looked at SARS-CoV-2 in pets of a “veterinary community” of 20 students. (I’m not really sure what the “veterinary community” means and it’s not described further.)
- Two of the students were diagnosed with COVID-19. Eleven others had signs of respiratory disease and were suspected cases.
- Nine cats and 12 dogs living with the students were tested for virus shedding by PCR, and also for the presence of antibodies in their blood.
- All of the pets were negative for both virus and antibodies.
That’s an encouraging result, but there are a couple of factors to keep in mind:
- This was a relatively small sample of pets. It’s a start, but we need larger studies. If we look at cats (the species we’re most concerned about), the prevalence of infection in this study was 0/9. However, the confidence interval would be 0-23%. That means the actual percentage of infected animals is likely to fall between 0 and 23%.
- The greater the sample size, the more confident we can be that zero really means zero. A prevalence study of the gender of Canadian kids conducted in my house would yield a result of 0/3 for boys. Since I’m pretty sure boys aren’t extinct, we can take comfort in a confidence interval that shows a much broader estimate.
- The study is also hard to interpret because of the lack of information about which animals had contact with the owners with confirmed or suspected COVID-19. We know where were 2 infected and 11 suspected cases, but we don’t know how many of the animals were owned by them, versus the other 7 students who were not sick. It’s not clear if all the pets were exposed to the virus, or how much exposure they may have had within the community.
So, it’s good to see a zero prevalence in the animals in this study, but we have to make sure we don’t over-react to this, just like we don’t want people to over-react to finding SARS-CoV-2 in an animal. It’s one more small step in the learning process when it comes to this virus. We need bigger studies, but it’s not easy to into infected households to test animals (as I know from our work), for obvious reasons .
There’s be an unprecedented amount of research done on SARS-CoV-2 in a very short time, and the number of publications that have already surfaced is astounding. At the same time, there’s a massive race to be “first” in the research world, leading to issues such as superficial studies or downright wrong conclusions (this isn’t directed at the study above, just a general statement about an issue we need to consider).
Many papers are getting uploaded to pre-print sites like BioRxiv, a relatively new platform whereby researchers can upload a paper to get it out in public before it’s undergone peer review. That can be very useful in an outbreak situation because it greatly speeds up the flow of information. However, it is likely that a large number of COVID-19 papers on pre-print sites will never be published because of quality issues. That creates a challenge, since you have to be able to interpret the quality of the science yourself, and you can’t rely on the peer review process to do it for you (and if it’s not your area of expertise, that can be pretty difficult).
The early suggestion that snakes were an intermediate host of SARS-CoV-2 got a lot of attention, but was pretty much debunked within 24 hours of publication. In contrast, an early experimental study of SARS-CoV-2 in animals got a lot of attention as a pre-print, and was published in the high impact journal Science shortly thereafter.
It’s just like breaking news on media sites – we need to pay attention because they may include important early warning information, but realize that the rush to be the first to break a story sometimes results in errors. Some breaking news ends up being (I cringe to use the term….) fake news. So, we need to keep the information coming but still scrutinize all the information we’re getting.