LOS ANGELES - Dr. Rochelle Walensky, director of the U.S. Centers for Disease Control and Prevention, said the next two months are critical for the nation to prevent a possible next wave of COVID-19.
"There is so much that's critical riding on the next two months," Walensky said, speaking at a National League of Cities virtual conference on Monday. "How quickly we will vaccinate versus whether we will have another surge really relies on what happens in March and April."
Walensky’s concern comes as the White House announced it will make an additional 900,000 doses of Pfizer and Moderna vaccines available to states and pharmacy partners this week.
White House press secretary Jen Psaki announced that states and territories will receive 15.8 million doses of the two-shot vaccines, up from 15.2 million last week. Another 2.7 million doses will be distributed through the federal pharmacy program this week.
Last week, President Joe Biden directed the pharmacy program to prioritize teachers and childcare workers. Psaki said the U.S. is now delivering an average of 2.17 million doses per day.
Biden has made vaccinating most of the country as soon as possible a priority in his administration.
Some lawmakers and health experts have urged that the U.S. needs to temporarily shift to a single-dose regimen for all COVID-19 vaccines so that doses are made more easily available to the general public.
Acting Health and Human Services Secretary Norris Cochran along with seven physician members of Congress wrote in a March 2 letter urging the department to "consider issuing a revised emergency use authorization as soon as possible" that might lead to single-dose use of the Pfizer and Moderna vaccines."
Citing various challenges in distributing COVID-19 vaccines to Americans, lawmakers say that some evidence supports the fact that the first dose of the Pfizer and Moderna vaccine appears to offer enough protection against the virus.
"Recent and re-examined data has demonstrated that both the Pfizer-BioNTech and Moderna COVID19 mRNA vaccines appear highly effective after only one dose to critical clinical endpoints, including transmission, hospitalization, severe disease, and mortality, relative to the two-dose regime currently authorized," the letter reads.
"As you know, vaccine distribution and administration has been met with challenges across the country," the letter continues. "Evaluating all available clinical data now would allow states to more widely administer a single dose of both the Pfizer-BioNTech and Moderna mRNA vaccines until all vulnerable and essential populations are inoculated, and more vaccine doses become available."
More than 60 million people, or 18.1% of the U.S. population, have received at least one dose of a coronavirus vaccine, according to the CDC. Some 31.2 million people have completed their vaccination with two doses, or 9.4% of the population.
According to data from Johns Hopkins University, the seven-day rolling average for daily new cases in the U.S. decreased over the past two weeks, going from 66,162.4 on Feb. 21 to 57,971.5 on Sunday.
The race to vaccinate the majority of Americans comes as medical experts continue to sound the alarm on the possibility of a coming COVID-19 surge involving one of the many viral mutations that have been identified across the globe.
A more contagious and possibly more deadly variant that was first identified in Britain has been found in at least 42 states. Other variants first detected in South Africa and Brazil have been reported across the U.S. in low numbers. The South Africa mutation is especially worrisome because of evidence it may diminish the effectiveness of the vaccines.
With some U.S. states, like Texas, dropping mandates to stop the spread of COVID-19 as more and more residents get vaccinated, medical experts are warning that these reopenings are premature and could lead to another deadly surge.
Scientists widely agree that the U.S. simply doesn’t have enough of a handle on the variants to roll back public health measures and is at risk of fumbling yet another phase of the pandemic after letting the virus rage through the country over the last year and kill nearly 500,000 people.
"Now is not the time to fully open up," said Karthik Gangavarapu, a researcher at Scripps Research Institute whose team works closely with San Diego health officials to watch for mutant versions of the coronavirus. "We need to still be vigilant."
The problem, as experts see it, is that the U.S. has been slow to ramp up a rigorous genetic surveillance system for tracking the variants’ spread and measuring how much of a foothold they have gained here.
"The fact of the matter is we’re kind of in the dark," said Dr. Diane Griffin, who studies infectious diseases at Johns Hopkins. She said the variants are "probably widespread even if we don’t know it."
"We’re chasing a moving target. It’s changing a little too fast for comfort," said Dr. Lucio Miele a geneticist at LSU Health Sciences in New Orleans. "We need to be proactive. We’re not invulnerable."
Detecting variants and knowing where and how widely they are spreading could be critical to preventing another deadly wave of COVID-19 like the one that overwhelmed hospitals this winter.
The Associated Press contributed to this story.