Why are COVID cases going down? Yahoo News Explains

The United States is seeing a large decline in new COVID-19 cases. According to the Centers for Disease Control and Prevention, new cases of the disease have declined for the fifth straight week, dropping by more than 24 percent. Yahoo News Medical Contributor Dr. Kavita Patel explains some of the reasons why this is happening and whether we might see a fourth surge driven by new variants.

Video Transcript


KAVITA PATEL: We are seeing the virus in retreat, or at least seeing very solid evidence around the country that cases are dropping at a very dramatic rate. Almost half each week, if not more. And there's several factors contributing.

Number one, and probably the most likely, is just kind of the ups and downs that we've seen with previous surges. Typically, as cases are skyrocketing and hospitals are overwhelmed, cities, counties, and states are putting much stricter measures in place. Eliminating indoor dining, eliminating any group settings where people can congregate. And that actually does materially help decrease cases. That's probably a big factor in this recent drop.

The second is, and it's some speculation around, what we call the seasonality of the virus. What that means-- and maybe an easier way to think about it is to think about the flu. Almost every winter we see an increase in flu virus cases but we don't see as much flu-- even though it exists-- in the summer. So there's a speculation that coronavirus has some seasonality. It's not the way we see the flu but similar, so that could be a driver.

A third but less likely is, to some degree, not just vaccines but some notion that a lot of people have now been infected. Right now we think that we are underestimating the number of Americans that are infected. We think it's about 10% by our testing. But there are many who think that that's double or triple in reality. And really, at the end of the day, the more people that have already been infected, the less physical bodies the virus has to try to infect. But it's hard to know without some data to back that up. But all in all, we're seeing a decrease.

We should continue to see these numbers get at least to where we started with in March. If you'll recall, even when we were at 1,000 or so cases a day, we were concerned about the coronavirus. It's only gotten worse since then, but we shouldn't get complacent because we are still in a pretty vulnerable period where cases are dropping but they still exist. Much of the nation is still in kind of what I would call a red category, with enough cases to be careful about reopenings. And, also, these variants which we know are more transmissible and highly likely to be contagious to others.


The next speculation is whether or not we will have a fourth surge. I do think we are going to see, in some parts of the country, an increase in cases in the next several months. It will likely not be as dramatic as this holiday season surge. But remember, in March and again in July we did see a certain degree of locality to the surges. We saw parts of the East and West Coast affected the most in March. And then in July, we saw other parts of the country that had not been affected in March.

We could see a similar pattern and that will have a lot to do with the level of vaccination in those communities, as well as the level of the extent of these variants. They are everywhere. But the extent to which they are driving the current infections will probably depend on what community you're in. So, again, a fourth surge feels like it's highly likely but at a much lower degree than this most recent one. And hopefully a much lower degree than the two previous ones in March and July.