The total number of cases nationwide fell in one 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 ditched virus restrictions and mask warrants, even indoors.
Experts said some states are seeing increased immunity due to high rates of natural spread of the disease, which has so far killed nearly 600,000 Americans.
“We are certainly getting population benefits from our previous cases, but we have paid for it,” said Dr. Thomas Dobbs, Mississippi state health official. “We paid for it with deaths. “
More than 7,300 Mississippians have died in the pandemic, and the state has the sixth highest per capita death rate.
Dobbs estimated that about 60% of the state’s residents have “some underlying immunity.”
“So we’re now sort of seeing that effect, most 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 – saw their seven-day moving averages for infection rates rise from two weeks earlier, according to data compiled by the Johns Hopkins University. All except Hawaii had vaccination rates below the US average of 39.7% fully vaccinated, according to the US Centers for Disease Control and Prevention.
The 10 states with the fewest new cases per capita during this period all have full vaccination rates above the national average. This includes the three most vaccinated states in the country: Vermont, Massachusetts, and Connecticut.
Medical experts said a host of factors are playing into the decline in the number of cases across the country, including vaccines, natural immunity to exposure to the virus, warmer weather and people spending less time. inside.
But Dr Leana Wen, professor of public health at George Washington University, said she was concerned that the natural immunity of those who have been exposed to the coronavirus will wane soon. And she fears states with low immunization rates could become hot spots.
“Just because we’re lucky in June doesn’t mean we’ll continue to be lucky through late fall and winter,” said Wen, the former health commissioner of the city of Baltimore. “We may well have more transmissible, more virulent variants here, and those with no immunity or waning immunity may be susceptible again. “
In Mississippi, about 835,000 people have been fully immunized, or 28% of the population, compared to 43% on the national average. But despite the lagging vaccination rate, the state’s moving average of daily new cases over the past two weeks has declined by about 18%, according to Johns Hopkins.
Dr Albert Ko, who chairs the Department of Microbial Disease Epidemiology at Yale, said there was no specific data to show what percentage of the population in “high burden” states like Alabama or Texas has been exposed to the virus, but he said estimates put it up to 50%.
“I think that doesn’t negate the importance of vaccination, especially because the levels of antibodies you get that are induced by natural infection are lower than what we have for our best vaccine,” said Kb.
Ko said it is important that even people exposed to the disease are vaccinated, because natural immunity does not last as long as vaccine immunity and antibody levels are lower.
Wen said research strongly suggests that vaccinations offer a benefit to those who already have antibodies from infection.
“I think it’s a mistake that a lot of people think recovery means they no longer need to be vaccinated,” she said.
Pat Eaton-Robb contributed to this report from Connecticut.