A single dose of Pfizer’s coronavirus vaccine may not generate a sufficient immune response to protect against dominant new variants, except in people who have already been infected with Covid-19, according to a UK study published on April 30.

According to separate studies, blood type does not affect susceptibility to Covid-19 in U.S. patients and an inhaled steroid commonly used to treat asthma can help keep patients with mild Covid-19 from getting sicker.

A new study by researchers at the University College London (UCL) published in Lancet Infectious Diseases finds that although the U.K. variant of SARS-CoV-2 known as B.1.1.7 is more transmissible than the wild-type, original Wuhan strain, it is likely not more deadly.

Shares of Inovio climbed in trading after the company announced its DNA vaccine candidate for Covid-19 induced a robust T-cell response against multiple variants of the SARS-CoV-2 virus.

Pfizer and BioNTech on March 31 announced data from a Phase III study which showed 100 percent efficacy and robust antibody responses in patients ages 12-15 years old who received the BNT162b2 vaccine.

The United States reported a 25% drop in new cases of Covid-19 to about 825,000 during the week ended Feb. 7, the biggest fall since the pandemic started, although health officials said they were worried new variants of the virus could slow or reverse this progress.

Moderna started development on a booster to the company’s Covid-19 vaccine, which is hoped to work against the recently discovered (and more transmissible) SARS-CoV-2 variant from South Africa.

The Covid-19 vaccine developed by Pfizer and BioNTech is likely to protect against a more infectious variant of the virus discovered in Britain which has spread around the world, according to results of further lab tests.

A new, highly transmissible variant of the coronavirus first discovered in Britain could become the dominant variant in the United States by March, the U.S. Centers for Disease Control and Prevention warned.