Following the Science – May 6, 2020
For this Science Wednesday, we’re sharing 10 key facts on SARS-CoV2, the virus, and COVID-19, the disease it causes, as written by Dr. Alan Townsend*, PhD in biological sciences (Stanford University), provost of Colorado College and former director of the Institute of Arctic and Alpine Research at the University of Colorado Boulder. He began working at the intersection of environment and health nearly three decades ago.
1) Don’t be deceived by arguments that COVID-19 is just like the flu. It’s not. Annual CDC mortality numbers for the flu take known cases each year and then use a model to project the real toll. If you use similar methods for COVID-19 – as we must to have a fair comparison – COVID-19 appears ten times worse or more, and that still does not account for potential long-term consequences of the disease for many survivors.
2) Herd immunity without a vaccine is not a public health strategy supported by any credible expert with a conscience, because it would have devastating consequences. Herd immunity can only be achieved in two ways. One, by widespread use of an effective vaccine. Two, by well over half the population being infected and recovered. The latter would create an enormous toll in human lives unless we find anti-viral drugs which substantially lower the risk of infection.
3) The search for both a vaccine and those anti-viral drugs is happening at an unprecedented pace. There are nearly 100 different vaccines currently in development, a few of which have moved to early human trials. There are some promising early results. No matter what, we won’t have a widely available vaccine in the next few months, but the prospects for one as fast as is possible are good.
4) Good anti-viral drug(s) can be nearly as effective as a vaccine. Why? They make the consequences of infection minor, and thus allow herd immunity to develop without high risk. You may have seen mixed news about remdesivir, a drug previously used against Ebola. The latest science shows real promise for it to be helpful with COVID-19 recovery, but also not a game-changer. Still, it’s a good step forward, and there are multiple other drugs which are in earlier stages of showing even greater promise.
5) Until we have a vaccine or good anti-virals, our own behavior is the only way to lower risk. The more we employ good public health practices, quite literally the more lives we save.
6) Masks matter, but only if widely used. An example: if 80% of us wear masks that are 60% effective (typical for a standard cloth mask), we can cut the transmission rate to a level where infections slow way down. Put another way, that would likely cut Ro below 1. Ro is the average number of people infected by each infected person. When that’s greater that 1, even by a little, you get exponential growth of cases. When it’s less than one, the spread slows. Absent intervention, Ro for SARS-CoV-2 varies but is usually between 2-3, if not higher in some places. That’s why the number of cases can grow so rapidly.
7) The main effect of season, if there is one, will come from human behavior, not temperature sensitivity. We tend to be outside and spread apart just a bit more in summer. That might help slow rates of infection, but absent other interventions will not eliminate the disease or the risk of a fall/winter resurgence. And a second summer wave as social distancing is relaxed is very possible.
8) COVID-19 is only the latest stark evidence of structural racism and inequity in this country. African American and Native and Indigenous communities are being hit by the disease at far higher rates than white communities. It’s a clear and devastating fact that has nothing to do with the biology of the virus or those infected, and everything to do with the socio-economic past and present of this nation.
9) The virus almost certainly did not originate from a Chinese laboratory. Every bit of credible evidence points to a spillover event from wildlife, and that is only the latest of many such events. HIV, Ebola, MERS, the first SARS and many more came from human-animal contact. This isn’t the first, and won’t be the last. With effort, however, we can both lower the risk of spillover events and stop their spread far more effectively than we have with this virus.
10) Science provides the best foundation for both our current decisions and our future hopes. Science is not perfect, good science takes time, and the pressure of this pandemic to move fast will increase the chance of jumping to premature conclusions. But we know a lot already about the best paths to take now, and the prospects for both helpful drugs and a vaccine are good. Epidemiological expertise should guide us now, building the best bridge to that welcome day when game-changing medical interventions become real.
*posted with permission.
image: CDC public domain