New COVID-19 cases are declining in most parts of the country, even in some states with vacant populations. But almost all states exploiting this trend have lower-than-average vaccination rates, and experts warn that relief from the pandemic could be fleeting in regions where few people are inoculated.
Total national cases decreased in a week from a seven-day average of nearly 21,000 on May 29 to 14,315 on Saturday, according to data from Johns Hopkins University. For weeks, states and cities have been abandoning virus restrictions and masking mandates, even internally.
Experts say some states are seeing increased immunity because there have been high rates of natural spread of the disease, which has so far killed nearly 600,000 Americans.
“We certainly got some benefit from the population from our previous cases, but we paid for it,” said Dr. Thomas Dobbs, Mississippi State Health Officer. “We paid for it with the dead.”
More than 7,300 Mississippians have died in the pandemic, and the state has the sixth highest death rate per capita.
Dobbs estimated that about 60% of the state’s residents have “some underlying immunity”.
“So we’re now sort of seeing that effect, very likely, because we have a combination of natural and vaccine-induced immunity,” Dobbs said.
Only eight states – Alabama, Arkansas, Hawaii, Missouri, Nevada, Texas, Utah and Wyoming – have seen their seven-day rotating average for infection rates rise from two weeks earlier, according to data compiled by Johns University Hopkins. All, except Hawaii, have recorded vaccination rates that are below the U.S. average of 43% fully vaccinated, according to the U.S. Centers for Disease Control and Prevention.
The 10 states with the fewest nine cases per capita in that time frame have all vaccinated rates above the national average.
Medical experts said a host of factors play a role in the decline in cases across the country, including vaccines, natural immunity from exposure to the virus, hot weather and people spending less time at home.
But Dr. Leana Wen, a professor of public health at George Washington University, said she is concerned that the natural immunity of those who have been exposed to the coronavirus may soon decline. And he fears states with low vaccination rates could become hot spots.
“Just because we’re lucky in June doesn’t mean we’ll continue to be lucky in the late fall and winter,” said Wen, the former health commissioner for the city of Baltimore. “We could see variants here that are more transmissible, more virulent and those that do not have immunity or have decreased immunity may be susceptible once more.”
In Mississippi, about 835,000 people were vaccinated in total, or 28% of the population. But despite the delayed vaccination schedule, the state’s rotating average number of new cases each day in the last two weeks has decreased by about 18%, according to Johns Hopkins.
Dr. Albert Ko, who chairs the Department of Epidemiology of Microbial Diseases at Yale, said there are no accurate data to show what percentage of the population in “high-load” states like Alabama or Texas are were exposed to the virus, but said estimates put it up to 50%.
“I think it doesn’t negate the importance of vaccination, especially because the levels of antibodies you get that are induced by natural infections are lower than what we get for our best vaccine,” Ko said.
Ko said it is important that even those exposed to the disease be vaccinated because natural immunity does not last so long that immunity to the vaccine and antibody levels are lower.
Wen said the research strongly suggests that vaccinations provide a benefit to those who already have some antibodies to the infection.
“I think it’s a lie that a lot of people have this recovery meaning they no longer need to be vaccinated,” he said.