Moderna Inc. said on May 5 early human trial data shows that a third dose of either the company’s current Covid-19 shot or an experimental new vaccine candidate increases immunity against variants of Covid-19 first found in Brazil and South Africa.

The United States is preparing for the possibility that a booster shot will be needed between nine to 12 months after people are initially vaccinated against Covid-19, a White House official said on April 15.

Russia registered the world’s first vaccine against Covid-19 for animals, the country’s agriculture safety watchdog Rosselkhoznadzor said on March 31.

Meissa Vaccines’ intranasal live attenuated chimeric virus-based vaccine for SARS-CoV-2 (and its variants), which was cleared for Phase I trials, employs codon deoptimization to evoke a stronger-than-usual immune response.

Public Health England (PHE) published real-world analyses of people in the U.K. who had received the first shot of the Pfizer-BioNTech Covid-19 vaccine, with the data – which were published in The Lancet – showing that there was a decrease of about 70 percent in infections among healthcare workers after the first shot.

Pfizer Inc. and BioNTech’s Covid-19 vaccine appeared to lose only a small bit of effectiveness against an engineered virus with three key mutations from the new coronavirus variant found in South Africa, according to a laboratory study conducted by the U.S. drugmaker.

Immunity from Moderna Inc.’s Covid-19 vaccine should last at least a year, the company said at the J.P. Morgan Healthcare conference.

Evidence continues to build for long-lasting immunity to Covid-19 following disease infection, with the publication of a new study showing a durable immune response as far as eight months after the initial onset of symptoms.

Leading U.S. infectious disease specialist Dr. Anthony Fauci said he foresees America achieving enough collective Covid-19 immunity through vaccinations to regain “some semblance of normality” by autumn 2021, despite early setbacks in the vaccine rollout.