COVID-19 cases and hospitalizations have dropped dramatically, but epidemiologists say it is probably too early for the coronavirus vaccines to be making the difference.
On Jan. 8, new daily cases of COVID-19 reached an all-time high of 295,121. The seven-day average was about 243,538. On Monday, the seven-day average had fallen to 87,073.
The number of patients hospitalized with the disease peaked on Jan. 6, while the number of those in intensive care units reached a high two days later. Since then, hospitalizations have dropped 51% and ICU hospitalizations have fallen 42%.
Yet, it seems unlikely the improvement is due to the vaccine campaign.
“I don’t think what we’re seeing is a vaccine effect yet,” said Dr. Georges Benjamin, executive director of the American Public Health Association. “The reason is that if you look at how much vaccine we’ve delivered … it is much too early.”
By Jan. 6, only about 8 million vaccines had been administered. By Tuesday, the number had reached over 55 million.
But Benjamin thinks that’s not enough to have had a decisive impact.
“That [55 million] is nationwide, so it is pretty diffuse,” he said. “I would anticipate a vaccine effect in the next few weeks, but not yet.”
Since the vaccine has been targeted heavily to the elderly, cases among the elderly should show a higher decline.
“All of the age groups are going down kind of the same way when you look at the state data,” said Susan Hassig, an epidemiology professor at the Tulane University School of Public Health and Tropical Medicine. “If it were a vaccine-related drop, you would expect older age groups that have been targeted for vaccination to be dropping more rapidly.”
While the federal government doesn’t track cases by age, many states such as California do. Since Jan. 6, daily cases among those age 65 and up have declined 84% in California, the same rate as for other age groups.
One reason for the decline is the Thanksgiving and Christmas holiday season is now more than six weeks in the past. Travel and gatherings at home likely played a role in the huge surge that began in November.
Benjamin also suggested increased mask-wearing and social distancing have contributed to the decline. Data from the Delphi Group at Carnegie Mellon University shows an increase in mask-wearing across the nation since early June. People have been slightly less mobile since early January based on data from Unacast, a location data firm. Data from Apple, though, shows no change.
Additionally, herd immunity may be playing a part, as people who have been infected are thought to gain protection, making it harder for the virus to circulate. There have been nearly 28 million confirmed cases of COVID-19 in the United States, although the number of infections is far higher, as many people with few or no symptoms never get tested.
Hassig pointed to another possible reason.
“Part of the reason it looks like we’ve dropped so much is that we were so high in early January,” Hassig said. “We’re lower, but we’re not low.”
The U.S. is still far above the peak of the summer surge, when daily cases averaged almost 63,000.
While the COVID-19 numbers are improving, experts warn more surges could still happen.
“We might see another surge because of the variants of the virus that are making their way into this country and, in some cases, are already here,” said Dr. Marissa Levine, a former state health commissioner in Virginia and director at the Center for Leadership in Public Health Practice at the University of South Florida.
The Centers for Disease Control and Prevention has confirmed 1,173 cases of the United Kingdom variant in the U.S., 17 of the South African variant, and three of the Brazilian strain. Likely infections are much higher. The strains are more transmissible than the standard virus. Vaccines may protect against these strains, but thus far, research on that is inconclusive.
