The perfect vaccine—one that protects against all strains of a given disease with no exceptions forever and ever—has never been invented, and given the mutability of viruses and the frailties of the human immune system, likely never will be.
That hard fact always made it possible that a booster dose of the COVID-19 vaccine would be necessary, and yesterday both the White House and the Department of Health and Human Services made it official: Beginning Sept. 20—pending approval by the U.S. Food and Drug Administration (FDA)—booster doses will be made available to all those in the U.S. who have received two doses of the Pfizer-BioNTech or Moderna vaccines, with the fresh shots to be administered eight months after people received their second dose. (The government is still compiling data regarding the single-dose Jannsen/Johnson & Johnson vaccine, and expects to have a recommendation in a few weeks.)
As my colleague Alice Park explains, there are three leading reasons for the new guidance:
For starters, the numbers: Data from a New York City study show that the COVID-19 vaccines' effectiveness in preventing infection dropped from 91.7% in May to 79.8% by the end of July. Another national study of nursing home residents conducted by the National Healthcare Safety Network found the shots' effectiveness against infection was 74.7% prior to the emergence of the Delta variant, but dropped to 53.1% by the end of July. Boosters may be able to bump those numbers back up.
Then too there's the business of the nasopharynx. Viral loads tend to be lower in the nasal passages of vaccinated patients compared to the unvaccinated, potentially making vaccinated people less likely to pass the virus along to others. Boosters could amplify or prolong that effect. "It's entirely conceivable that [boosters] would be important in lowering the level of virus in the nasopharynx, which could impact transmission," White House chief medical adviser Dr. Anthony Fauci said at a press briefing yesterday.
There is also the matter of breakthrough infections, in which vaccinated people test positive for the virus (and sometimes develop symptoms). According to data from Israel, 341 out of 100,000 people who received two doses of the Pfizer-BioNTech shot by January tested positive by early August, compared to just 196 out of 100,000 who had been fully vaccinated by February. That trend continues through the year, suggesting that the immunity provided by the vaccine wanes over time.
While the FDA has yet to authorize the move, the U.S. Surgeon General defended the timing of the White House announcement, noting that the heads-up was designed to give states the opportunity to prepare for what will likely be another sudden increase in demand.
There's no guarantee that people who receive a third shot won't suffer a breakthrough infection or pass along the virus to someone else. "These vaccines were never intended to be a force field," Dr. Kirsten Lyke, professor of medicine at University of Maryland, told Alice. Still, the shots are powerful and they're effective, and the government has determined—rightly, the data strongly suggest—that an additional dose, properly timed, can make them even more so.
About 422.1 million doses of the COVID-19 vaccine have been shipped to various U.S. states as of this afternoon, of which nearly 359.6 million doses have been administered thus far, according to TIME's vaccine tracker. About 51.1% of Americans have been completely vaccinated.
More than 209.3 million people around the world had been diagnosed with COVID-19 as of 3 a.m. E.T. today, and nearly 4.4 million people have died. On August 18, there were 707,808 new cases and 10,814 new deaths confirmed globally.
Here's how the world as a whole is currently trending:
Here's where daily cases have risen or fallen over the last 14 days, shown in confirmed cases per 100,000 residents:
And here's every country that has reported over 4 million cases:
The U.S. had recorded more than 37.1 million coronavirus cases as of 3 a.m. E.T. today. More than 624,000 people have died. On August 18, there were 137,815 new cases and 1,145 new deaths confirmed in the U.S.
Here's how the country as a whole is currently trending:
Here's where daily cases have risen or fallen over the last 14 days, shown in confirmed cases per 100,000 residents:
All numbers unless otherwise specified are from the Johns Hopkins University Center for Systems Science and Engineering, and are accurate as of Aug. 19, 1 a.m. E.T. To see larger, interactive versions of these maps and charts, click here.
WHAT ELSE YOU SHOULD KNOW
U.S. President Joe Biden and First Lady Jill Biden will lead by example, receiving their coronavirus booster shots as soon as they become available in September, Biden told ABC's George Stephanopoulos today on Good Morning America. "We got our shots all the way back in, I think, December, so it's past time," the President said. The interview was taped yesterday, hours before the White House said boosters would be approved for the vaccinated public at large.
Vaccinations have prevented nearly 140,000 U.S. COVID-19 deaths as of May 9, according to a study supported by the National Institute on Aging. The researchers, who created a model to determine an association between state-by-state data on weekly vaccination rates and the death rate among the unvaccinated, calculated that 709,000 deaths would have occurred in the U.S. without vaccinations, compared to the 570,000 that actually did occur. The researchers acknowledge that the study cannot fully tease out the impact of vaccines from the role that natural immunity and social distancing may have also played in reducing the death rate.
Plastic barriers intended to block the transmission of the coronavirus may be doing more harm than good,according to The New York Times. The barriers are designed to separate workers from customers, or to separate customers from one another. In a room without barricades, however, air is typically circulated and replaced every 15 to 30 minutes. With barricades in place, circulatory dead zones may be created, preventing normal air clearance and allowing virus-carrying aerosols to linger and accumulate.
With Delta variant cases rising, Washington governor Jay Inslee yesterday issued an order bringing back statewide mask mandates and ordering public, private and charter school employees to get vaccinated as a condition of their employment,reports The Seattle Times. People opposed to vaccines or state mandates have protested the decision, but Inslee is holding firm and moving fast: his indoor mask mandate, which covers both the vaccinated and unvaccinated, goes into effect Aug. 23.
Alabama has officially run out of intensive care unit beds,reports The New York Times. So severe is the shortage that the state actually has a negative 29 ICU availability, meaning 29 patients in need of intensive care are waiting in emergency rooms for beds to open up. Only 47% of Alabama residents are at least partly vaccinated, below the national rate of about 57%. The state's seven-day hospitalization average hit 2,603 on Monday, dramatically up from a low of 252 on June 26.
President Biden has ordered Education Secretary Miguel Cardona to push back against governors who forbid school districts from instituting mask mandates for students,reports The Washington Post. In a blog post yesterday, Cardona announced that his department would investigate any state educational agency that takes actions that "may infringe on the rights of every student to access public education equally." That policy would apply especially in the case of children with medical conditions who would be threatened by a lack of masking, denying them a chance to "receive a free, appropriate public education," he added.
Thanks for reading. We hope you find the Coronavirus Brief newsletter to be a helpful tool to navigate this very complex situation, and welcome feedback at coronavirus.brief@time.com. If you have specific questions you'd like us to answer, please send them to covidquestions@time.com.
If you were forwarded this and want to sign up to receive it daily, click here.
Today's newsletter was written by Jeffrey Kluger and edited by Alex Fitzpatrick.
沒有留言:
張貼留言