Two new sublineages of the Omicron coronavirus variant can dodge antibodies from earlier infection well enough to trigger a new wave, but are far less able to thrive in the blood of people vaccinated against COVID-19, South African scientists found.

Pfizer Inc. and the company’s partner BioNTech SE said on April 26 that they had submitted an application to the U.S. health regulator for the authorization of a booster dose of their COVID-19 vaccine for children aged 5 to 11 years.

CureVac and GSK’s second-generation vaccine candidate targeting two recent COVID-19 variants has been shown to be highly effective in preclinical studies on mice, CureVac said, as the biotech firm seeks to catch up with rivals’ development work.

COVID-19 cases and deaths are declining in the Americas, the Pan American Health Organization (PAHO) said on April 20, with infections last week having dropped 2.3 percent and deaths falling 15.2 percent from the prior week. The broad trend comes even as cases have scaled up in North America with an 11.2 percent increase last week, the organization said.

A fourth dose of the COVID-19 vaccine from Pfizer and BioNTech provided significant added protection against severe disease, hospitalization and death for at least a month in older individuals, according to a study from Israel conducted when the Omicron variant was dominant. Additionally, new findings suggest patients with COVID-19 may have an increased risk of rare vision-threatening blood clots in the eye for months afterward.

A third dose of the COVID-19 vaccine from Pfizer (PFE.N) and BioNTech (22UAy.DE) produced significant protection against the Omicron variant of the coronavirus in healthy children ages 5 to 11, the companies said on April 14.

Pfizer Chief Executive Albert Bourla said on April 13 that the company could possibly develop a new vaccine that protects against the Omicron variant as well as older forms of COVID-19 by autumn.

An experimental drug being developed by RedHill Biopharma Ltd. that improved outcomes in a randomized trial involving severely ill COVID-19 patients infected with earlier versions of the coronavirus is showing promise against the Omicron variant in test tube experiments, researchers said. Additionally, people living with well-controlled HIV infections are likely to have immune responses to the mRNA COVID-19 vaccines from Moderna and from Pfizer/BioNTech similar to those of otherwise healthy individuals, according to new data.

The global vaccine alliance Gavi has secured $4.8 billion in funding pledges for the vaccine-sharing scheme COVAX, an official said on Friday, falling just shy of its target.

Top U.S. Food and Drug Administration officials on April 6 said the agency is aiming to decide by June whether to change the design of COVID-19 vaccines in order to combat future variants, even if it does not have all the necessary information to measure their effectiveness.