Monday, Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention (CDC), that the seven-day average of COVID-19 cases reached 67,440 cases per day. That was a marked increase from a month ago – when, as Walensky noted, the seven-day average was “just over 53,000 a day.
“Unfortunately, the seven-day average of daily deaths is now increasing, with six consecutive days of increases, to about 695 deaths per day,” Walensky said.
The slow increase in COVID-19 cases across the country may seem inconsistent with another fundamental public health fact: In the same time, tens of millions of Americans have been fully vaccinated against the new coronavirus, which causes COVID-19. According to the CDC, more than 50 percent of American adults 18 and older in the US have received at least the first dose of the vaccine; nearly 25 percent of the population is fully vaccinated. As Walensky pointed out Monday, that means more than 84 million have been fully vaccinated; and of those vaccinated, the US has had less than 6,000 “breakthrough infections” with fully vaccinated subjects testing positive for COVID-19.
Given the rapid rollout of vaccinations, the news of an increase in the number of cases may seem very strange. Indeed, shouldn’t cases start to decline as more people are vaccinated?
Dr. Amesh Adalja, a senior scholar at the Johns Hopkins Center, said the reasons for this are related to demographics – specifically, who is vaccinated and who isn’t.
“If you look at the demographics of the cases that do occur, they are often in the twenty to thirty years of age group that has largely not been vaccinated,” Adalja said. “I think it will take some time for the cases to recede as the vaccine gets through to that population.”
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In fact, until this week, availability in all states was primarily based on age ranges; only now are COVID-19 vaccines available for people in their 20s and 30s. And indeed, younger adults seem to be the ones who are infected. Last week, the Conway Daily Sun in New Hampshire reported that younger people were responsible for nearly half of the new COVID-19 cases in the state. Young people are also believed to be the cause of fluctuations in states like Michigan, where young people are hospitalized.
Adalja said he thinks the US will see cases drop if a higher proportion of the population is vaccinated – maybe about 40 percent, which he says could be a tipping point.
“All you have to do is look at a country like Israel, where they’ve been able to vaccinate a large portion of their population, and once they got to around 40 percent, you started seeing cases,” Adalja said. “It is difficult to know exactly when we will cross that threshold, because the threshold will be crossed by a combination of natural infection and vaccination-induced immunity.”
Adalja noted that “one of the biggest obstacles now will be the reluctance to vaccinate.”
According to an Axios-Ipsos poll conducted last week, 30 percent of those surveyed said they would be “not at all likely” or “not very likely” to be vaccinated when possible. 20 percent of those surveyed said, “I will not get the vaccine” after the vaccine becomes available to them.
Monica Gandhi, an infectious disease physician and professor of medicine at the University of California-San Francisco, told Salon that it is difficult to make general statements about this trend across the country as the pandemic varies across the country. “It’s like there are nearly 50 different pandemics going on across the country,” mused Gandhi.
Gandhi noted that 50 percent of the new cases come from a few states: Minnesota, Michigan, New York, Florida, and Pennsylvania. One metric that Gandhi looks at is what she calls the “number of hospital admissions per case,” which keeps track of the number of cases leading to hospital admissions.
“They are starting to disconnect, and what I mean by disconnection is that the same number of cases does not lead to the same number of hospitalizations as before,” Gandhi said. “I think that’s because of vaccinating our older individuals first.” In other words, fewer COVID-19 cases lead to hospitalization, which is a good sign.
However, Gandhi said that large numbers of younger people who become infected will also lead to an increase in hospital admissions. Gandhi also pointed to Israel as an example of how the US could expect to reach a turning point.
The spread of highly transmissible variants may play a role in the increase in the number of cases across the country, but Gandhi said this is probably not the only reason why. The COVID-19 strain known by B.1.1.7., Which was first identified in the UK, is believed to be 40 to 70 percent more transmissible.
“I’m sure I’m sure that in places where B.1.1.7 is circulating, as was true in Israel, it appears to have increased portability and I’m sure it contributes,” Gandhi said. “That cannot be the only reason, however, because there are places with the same percentage of variants and without the peaks.”
Gandhi said another contributing factor to the rise in the US could be people’s tendency to congregate, along with the degree of natural immunity of a state’s population. But she said she hoped the “tipping point” could be approaching where the number of cases begins to decline nationwide.
“I think we are very, very close,” said Gandhi.