While attention has been focused on the worrying new variants of SARS-CoV-2, there has been some good news: despite the evolution of a number of strains that appear to spread more readily, total COVID-19 cases have been dropping, both in the United States and globally. While there are a number of nations that are still seeing an increase in infections, a combination of reduced post-holiday spread and increased social interventions appear to be getting the surges seen in January under control.
That said, there are worrying signs that, at least in the US, a number of states are making the same mistakes that ensured that the virus never really went away after the first surge in cases. And the spread of many new variants drives home the need to avoid complacency.
Going down
The general fall in cases came up at a recent press briefing from the World Health Organization. “For the third week in a row, the number of new cases of COVID-19 reported globally fell last week,” said WHO Director-General Tedros Adhanom Ghebreyesus. “There are still many countries with increasing numbers of cases, but at the global level, this is encouraging news.”
The United States has been part of that trend. In the States, cases reached a peak in mid-January and have been declining since. As of the end of January, levels had dropped to where they were back in early November. (Deaths remain high due to the significant lag between diagnosis and mortality but would be expected to begin falling soon.) Even with the drop, however, daily cases are still well over three times what they were during the first peak of the pandemic in April and about double the levels seen during the US’ summertime surge.
The US’ drop appears to be taking place prior to some of the more infectious coronavirus variants becoming widespread. But there is some reason for optimism, as even countries where these variants are common, such as the UK, are seeing a significant drop in cases. This suggests that at least some of the surge in cases was driven by socializing done over the winter holidays, which many health experts feared would lead to increased cases.
But the WHO’s Dr. Tedros also suggested that social restrictions put in place in response to rising cases have also played a role. “It shows this virus can be controlled, even with the new variants in circulation,” he said. “And it shows that, if we keep going with the same proven public health measures, we can prevent infections and save lives.”
Who needs health measures?
Tedros, however, also sounded a note of caution, saying, “We have been here before. Over the past year, there have been moments in almost all countries when cases declined, and governments opened up too quickly, and individuals let down their guard, only for the virus to come roaring back.” That caution is backed up by multiple studies that indicated states and countries that raised their restrictions too early saw continued infections and earlier returns to widespread infections.
This is a basic outcome of viral spread. The drop in cases is a result of social restrictions, either mandatory or voluntary, lowering the rate at which each infected individual passes the virus on to others. The ultimate goal of these restrictions is to lower the overall cases so that, when people start everyday activities again, there are very few infections, allowing contact tracing and isolation to limit the virus’s spread. Stop the social restrictions too soon, and a lot more people will be infected, making contact tracing ineffective and starting new infections at a very high level.
That’s what seems to have happened in the United States, which never saw distinct waves of infections but instead had a number of peaks standing out from a backdrop of high levels of viral spread.
Unfortunately, the US seems dedicated to revisiting its earlier mistakes. At a time when infections are still well above any point prior to November, a number of states have responded to the drop in new cases with plans to lift restrictions. While California has been somewhat cautious and only lifted a stay-at-home order after ICU capacity rose last week, areas within the state are already allowing restaurants to reopen.
New York is taking a similar approach: restrictions have been lifted in much of the state, and indoor dining will resume in less than two weeks. The Empire State is also already planning to allow weddings with up to 150 people in March. These actions come as The New York Times reported that many key health officials have quit during the pandemic due to conflicts with New York Gov. Andrew Cuomo. In that article, Cuomo is quoted as saying he doesn’t trust his own experts.
About those new variants…
Easing restrictions this early is also a concern because it’s clear that the three most concerning variants are now circulating within the United States, even though they don’t appear to be widespread yet. These variants have the potential to offset some of the benefits of social restrictions or increase the speed of the virus’s spread in their absence.
To get a sense of the problems that the combination of new SARS-CoV-2 variants and ending restrictions might create, let’s look at the Brazilian city of Manaus. There, an initial wave of infections back in May hit extremely hard, and studies of blood donations indicated that as much as 75 percent of the population had been infected by October. One draft manuscript even suggested that the low rate of infections that followed this wave was an indication that the region might have reached herd immunity. As infections waned in late July, social restrictions were eliminated. After months in which infections remained low, entertainment venues were reopened in December.
And now the pandemic is back in Manaus, as described by a recent paper in The Lancet. Local authorities tried to impose social restrictions in response to the upswing in new cases, but they backed off in response to strong public resistance. With the limits lifted, a severe second wave of infections has struck the city.
In the new paper, some of the researchers who have been studying Manaus offer four potential reasons. One is simply that earlier studies had overestimated the number of people who had been exposed in the first wave. A second option is that we’re seeing the impact of fading immunity. While a number of cases of reinfection have been reported, the number of confirmed second cases remains low, and it’s not clear whether that’s due to limited testing or not.
Wear a mask
Related to that option is the possibility that some of the strains now circulating in Manaus have picked up enough mutations to avoid the immune response generated by the first wave of infections. Finally, it’s possible that some of these strains are simply more infectious and are doing better at reaching the population that went through the first wave without an infection. Obviously, more than one of these four factors may be at play during the recent surge in infections.
Manaus isn’t typical of the experiences of other cities in Brazil, so this is not to suggest that the US should expect to see an equivalent spike of infections as these and other strains become more common here. But the possibility can’t be excluded, either, which is why limiting the spread of infections through mask use and social restrictions will remain critical even as the post-holiday case spike fades.
https://arstechnica.com/?p=1739163