JUNE 2, 2021
Memorial Day will be the first major test of the effectiveness of Covid-19 vaccinations in the U.S., according to many epidemiologists.
Last year, reopenings in parts of the U.S. ahead of the holiday weekend led to a second surge of new coronavirus cases. Hospitalizations climbed in late June, followed by a steady rise in fatalities after the first week of July.
This year, epidemiologists and public-health officials are hopeful that despite millions of Americans traveling for the weekend and the broad rollback of pandemic restrictions, newly reported Covid-19 cases, hospitalizations and deaths will remain low as more of the country continues to get vaccinated, albeit at lower rates.
“We have seen after holiday weekends in the past that cases have risen, but we’ve never been in a position where we’ve had almost half the adults of America vaccinated and protected from this virus,” said Centers for Disease Control and Prevention Director Rochelle Walensky last week.
Dr. Walensky nevertheless warned the virus remained dangerous for the unvaccinated. She encouraged those who hadn’t gotten a Covid-19 shot to do so and in the meantime continue wearing masks and practicing physical distancing.
Nearly two million travelers took to the sky on Friday, the most flying Americans have done since the pandemic began.
A new phase of the U.S. pandemic is starting, as many Americans make summer travel plans and more states lift guidance for businesses and other gatherings. A total of 34 states are fully reopened, and 16 are in the process of easing restrictions, according to research from the Kaiser Family Foundation. In 32 states, there are no face-mask requirements. In 36, all nonessential businesses have reopened.
“If there is no spike, that is very good news and indicates that the national vaccination strategy is working and that we have reduced the number of susceptible people in the country to below the level where a sustained upsurge in new cases can occur,” said Philip Landrigan, an epidemiologist and director of the Program for Global Public Health and the Common Good at Boston College.
Dr. Landrigan said the potential impact of Memorial Day travel and gatherings wouldn’t be known until 14 to 21 days after the weekend.
On Monday, the seven-day average in newly reported cases nationwide fell below 20,000 for the first time since March 31, 2020, according to data from Johns Hopkins University. Deaths also remained near record lows, and over half the adult U.S. population is fully vaccinated, according to the CDC.
“Our outlook continues to improve, but there are still too many people yet to be vaccinated to feel completely safe as a whole,” said Ajay Sethi, an associate professor at the University of Wisconsin–Madison.
Dr. Sethi said he wouldn’t be surprised to see an increase in cases within communities with low vaccination rates, but he didn’t expect the kind of surge the country saw last summer.
According to the latest CDC data, 51.7% of the adult population in the U.S. is fully vaccinated. Many public-health experts say a population vaccinated above 40% is an important threshold past which inoculations gain the upper hand over the virus.
Rajesh Nandy, associate professor of Biostatistics & Epidemiology at the University of North Texas Health Science Center at Fort Worth, said the current vaccination percentage and total number of new infections suggest the U.S. is close to basic herd immunity.
“I do not expect to see a huge spike in the number of cases based on the estimated immunity level across the country,” Dr. Nandy said. “There may be a bump as we have seen during the spring break in some places, but we are in an even better position currently.”
Vaccinations, combined with a less-overwhelmed healthcare and public-health infrastructure, also will allow for a more rapid response and mitigation if local outbreaks do occur, said Saskia Popescu, an assistant professor and infectious disease epidemiologist at George Mason University.
National data show a lag in vaccinations across the South, a development that some epidemiologists and public-health officials worry could lead to a rise in summer infections. In general, the rate of vaccinations has slowed in recent weeks, and regional numbers vary.
President Biden outlined new initiatives Wednesday to push more Americans to get vaccinated ahead of his July 4 goal of having at least 70% of adults receive one shot.
The initiatives include free, drop-in child care appointments offered by four major child care providers—KinderCare, Learning Care Group, YMCA and Bright Horizons—for those who want to get vaccinated. Pharmacies administering vaccine doses will stay open for 24 hours on Fridays in June, and more businesses will offer incentives for vaccinated people, like sweepstakes and free beer.
“We need everyone across the country to pull together to get us over the finish line,” Mr. Biden said.
Epidemiologists are also looking beyond Memorial Day to the Independence Day holiday, which, combined with expected hotter weather, will force many people indoors and into air-conditioned spaces.
“This is certainly a first test but we won’t know what the impact is for three to four weeks and at that point we will be approaching July Fourth, which is perhaps an even bigger test,” said Vikas Parekh, a professor of internal medicine at the University of Michigan.
Many epidemiologists viewed the decline in the seven-day average in new cases nationwide to below 20,000 as encouraging news, but still too high for public-health officials to let their guard down.
“The end is in sight but we need to make sure that we meet the vaccination targets to be in a truly safe situation,” said Dr. Nandy.
Taking into account the county’s current testing capacity, the number of positive cases is as low as the U.S. has seen since early summer 2020, according to Dr. Parekh. “I would of course like to see cases fall even lower as this is still a much higher rate than, for example, Israel,” he said of the country with one of the world’s highest vaccination rates.
Dr. Landrigan, the professor at Boston College, was more blunt in his assessment: “It is still too high to completely relax.”