CNN  — 

Coronavirus infections across the US are still on the way down, and more Americans are getting vaccinated – but variants could cause complications soon.

Several experts predicted the highly contagious B.1.1.7 variant first detected in the UK is likely to fuel another surge of cases in just a matter of weeks.

“It could result in more of a wave in, say, April or May than we would have expected otherwise,” Trevor Bedford, of the University of Washington and the Fred Hutchinson Cancer Research Center, said during a briefing sponsored by the center on Tuesday. “But I still do suspect that things will be brought under control in the summer, and there will be very little virus circulating.”

The US Centers for Disease Control and Prevention is preparing for that, Andy Slavitt, the White House senior adviser for the Covid-19 Response Team, said Wednesday.

The CDC estimates that the variant will be the predominant one “by mid to late March,” CDC Director Dr. Rochelle Walensky said Wednesday at a webinar held by the American Public Health Association.

The predicted surge is why many experts highlight the need to double down on safety measures such as face masks, social distancing and avoiding crowded areas. Helping to lower cases will also reduce the virus’ chance to spread more and mutate, experts have said.

Still, an ensemble forecast Wednesday by the CDC projected 526,000 to 548,000 coronavirus deaths in the US by March 20. The previous forecast, published in February, projected up to 559,000 deaths by March 13.

Vaccinating as many people as possible will also be a big help in slowing any more surges – and the vaccine arsenal may be bolstered soon.

Johnson & Johnson’s single-dose Covid-19 vaccine has met the US Food and Drug Administration’s requirements for emergency use authorization, or EUA, the agency said Wednesday in an analysis.

The efficacy of the Johnson & Johnson vaccine against moderate to severe/critical Covid-19 across all geographic areas was 66.9% at least 14 days after the single dose vaccination and 66.1% at least 28 days after vaccination, states the analysis for the FDA’s Vaccines and Related Biological Products Advisory Committee, independent group of FDA advisers.

An analysis of the Johnson & Johnson vaccine “supported a favorable safety profile with no specific safety concerns identified that would preclude issuance of an EUA,” according to a 62-page briefing document released by the FDA on Wednesday.

The advisory committee meets Friday and will consider the documents and make a recommendation about whether Johnson & Johnson’s vaccine should be authorized.

Pending emergency use authorization, the Biden administration is preparing rollout plans for 3 million to 4 million doses of the Johnson & Johnson vaccine next week, White House Covid-19 response coordinator Jeff Zients said.

White House press secretary Jen Psaki said the administration was “surprised” when Johnson & Johnson told them they were behind on manufacturing. CNN has reported the initial number of doses was expected to be closer to 10 million.

“We’re going to continue to work with them on ensuring that that can be expedited,” Psaki said of Johnson & Johnson.

Still, the new, infectious variants make it “difficult to prevent a fourth wave altogether,” said Dr. Josh Schiffer, an infectious diseases specialist at Fred Hutchinson.

To speed up vaccinations, one report suggests the US should consider skipping second doses for now of two-dose vaccines produced by Pfizer/BioNTech and Moderna. People over 65 should go to the front of the line since they’re by far the most vulnerable to severe disease and death, according to a recommendation from Mike Osterholm and his colleagues at the University of Minnesota’s Center for Infectious Disease Research and Policy.

The group called on the FDA and CDC vaccine advisers to be quickly convened and determine whether data supports the group’s recommendations, including deferring second vaccine doses to after the coming surge.

“There is a narrow and rapidly closing window of opportunity to more effectively use vaccines and potentially prevent thousands of severe cases, hospitalizations, and deaths in the next weeks and months,” the report said.

Officials, including Dr. Anthony Fauci, have said in recent days the US is continuing to vaccinate people with both doses and close to the recommended schedules, with Fauci telling CNN earlier this week, “science points directly toward continuing with what we know about from the clinical trial.”

A pharmacist fills syringes with doses of Pfizer's Covid-19 vaccine at a pop-up community vaccination center in Valley Stream, New York, this month

Promising news about South African variant

Moderna announced that it has designed an updated version of its vaccine to help combat the South Africa coronavirus variant. Initial doses have been shipped to the US National Institutes of Health for a clinical study.

The new Moderna vaccine, called mRNA-1273.351, will be evaluated as a booster shot for people who have been vaccinated and as a primary vaccine for people who haven’t had the virus and have yet to be vaccinated.

Meanwhile, Johnson & Johnson, could get the green light for its own Covid-19 vaccine from the FDA later this week.

The Johnson & Johnson vaccine seems to work better against the variant first identified in South Africa than data initially suggested, according to the FDA briefing document.

The vaccine showed a 64% efficacy rate in South Africa – seven points higher than what was reported in interim company data in January, the FDA said. Since that time, Johnson & Johnson did additional sequencing and determined there were more cases that could be included in its analysis from South Africa.

Early research raises concern about UK variant in California

So far, more than 1,900 cases of coronavirus strains first spotted in the UK, South Africa and Brazil have been reported across the US, CDC data shows.

The vast majority of those cases – about 1,881 – are of the B.1.1.7 variant that’s concerning experts and that the CDC has previously warned could become the predominant variant by next month.

Meanwhile, two studies that are due to come out soon also raise concerns about the variant’s impact in California.

The studies hint that the variant might not only be more contagious but may also cause more severe disease. But the research is in its very early stages, has not been published or peer-reviewed and needs more work, researchers stressed.

A team at the University of California, San Francisco, tested virus samples from recent outbreaks across the state and found it was becoming far more common: while it wasn’t seen in any samples from September, by the end of January it was found in half of the samples.

The researchers also found some evidence suggesting the variant is more dangerous, writing in a report that they observed “increased severity of disease” associated with the variant, including “increased risk of high oxygen requirement.”

A second team at Unidos en Salud – a volunteer-led collaboration between UC San Francisco and other groups that offers fast Covid-19 testing in San Francisco’s Mission District – tested more than 8,800 people in January and sequenced the virus from more than 630 positive samples. They also found a rapid increase in the variant.

FDA may OK storing Pfizer vaccine at standard temps

Concerned about the variants, US officials continue to work to ramp up vaccinations.

The New York Times reported Tuesday the FDA plans to authorize a request from Pfizer allowing the vaccine maker to store its vaccines at regular freezer temperatures instead of the ultra-cold levels required up to now.

Pfizer and its partner BioNTech submitted data to the FDA on Friday showing its vaccine can be safely stored at temperatures higher than what is currently required for long-term storage. The Times quoted two sources familiar with the companies, who requested anonymity, saying the FDA informed the companies it would OK that request.

The move could greatly ease logistics for not just the companies, but the federal government, states and other groups that have been working to distribute those vaccines.

That piece of news comes as Pfizer and Moderna pledged to make a combined total of 220 million doses available for shipment by the end of March.

Moderna said Wednesday that approximately 55 million Covid-19 doses have been shipped to the US government. Additionally, approximately 33 million doses have been produced, filled into vials and are in the final stages of production and testing before release, according to a company statement.

So far, about 44.5 million Americans have received at least their first dose of a Covid-19 vaccine, according to CDC data. More than 19.8 million have been fully vaccinated – a little more than 6% of the US population.

The supply of Covid-19 vaccine doses allocated to states and retail pharmacies is increasing nearly 70%, from 8.6 million doses in January to 14.5 million doses this week, Zients said Wednesday.

Among one of several challenges that states are facing while getting shots in arms is racial disparities.

In California, officials said it will make changes to the statewide Covid-19 vaccine-appointment system after access codes distributed to underserved communities were used by outsiders to secure vaccines.

Recent data shows that Black and Latino residents collectively have received a combined 19% of the state’s vaccine doses while accounting for nearly 60% of California’s Covid-19 cases. In contrast, White residents have been given 32.7% of vaccine doses while making up about 20% of the state’s cases.

CNN’s John Bonifield, Maggie Fox, Sarah Moon, Cheri Mossburg, Amanda Sealy and Michael Nedelman contributed to this report.