Testing is under way for modified versions of COVID-19 vaccines that aim to deal with coronavirus variants. Experts say current vaccines still seem to work against the variants and prevent the most severe forms of disease, though the evidence is limited. Making changes may not be necessary for all the vaccines.  “We don’t know yet,” said Emory University Vaccine Center Associate Director Walter Orenstein. “But people want to get prepared just in case we need to.” Testing and manufacturing will likely take months, he said, so now is the time to get started. All major Western manufacturers with shots in use have announced studies involving either new shots targeted against a specific variant or additional booster shots of their existing vaccines. A woman reacts to seeing a syringe of the Sinovac vaccine for COVID-19 as health workers vaccinate residents in the Kalunga Vao de Almas quilombo on the outskirts of Cavalcante, Goias state, Brazil, March 16, 2021.The A pharmacist prepares to fill a syringe with the AstraZeneca COVID-19 vaccine at the Vaccine Village in Antwerp, Belgium, March 16, 2021.B.1.351 shares mutations with a strain first found in Brazil, where cases are surging. These mutations are thought to help both viruses spread more easily and also make them less susceptible to the effects of the vaccines. A vaccine against one variant may protect against both, said Baylor College of Medicine vaccine expert Peter Hotez. “The hope is that they’ll be close enough that [one variant vaccine] should cross-protect,” he said. “But these studies take time, so we don’t know for certain.” Moderna’s shot was less potent against B.1.351 in test tube studies, but still appeared strong enough to work. The company announced earlier this month that it had A man receives a dose of the Moderna vaccine against the coronavirus, at the Music Auditorium in Rome, Italy, March 17, 2021.Like Moderna’s shot, the Pfizer-BioNTech vaccine suffered in A nurse fills a syringe with a dose of the Pfizer-BioNTech COVID-19 vaccine at Zinga Zanga village hall vaccination center in Beziers, southern France, March 17, 2021.Both the Moderna and Pfizer-BioNTech vaccines are easier to change than earlier types of vaccines, which used dead or weakened germs or germ parts to trigger the immune system. The Moderna and Pfizer-BioNTech shots are genetic recipes for those parts, not the parts themselves.  “It’s relatively straightforward to swap out the genetic recipe for an earlier variant with a newer variant,” said William Moss, executive director of the Johns Hopkins University International Vaccine Access Center. “Technologically, that’s not a big lift.” Booster dose While that remains an option, Pfizer-BioNTech said in February that they are focusing mainly on testing a third, booster dose of their original vaccine. Further strengthening the immune response might overcome a variant’s ability to evade it.  FILE – A health worker loads syringes with the vaccine on the first day of the Johnson & Johnson vaccine being made available to residents at the Baldwin Hills Crenshaw Plaza in Los Angeles. California, March 11, 2021.One of the biggest advantages of this vaccine is that it only requires one dose, while Moderna and Pfizer-BioNTech take two. But Johnson & Johnson announced last November that it was testing the effects of a second dose. The AstraZeneca-University of Oxford vaccine took the biggest hit from B.1.351: just 10% effective against mild to moderate illness in a study published Wednesday. The study did not test how well it works against severe disease and death. Experts expect that it does still provide protection, though that has not been studied yet.  Lead developer Sarah Gilbert at the University of Oxford told the BBC that she expected a modified version against B.1.351 would be ready by late this year. The AstraZeneca vaccine is the one most widely used in the World Health Organization-backed COVAX vaccine distribution program.   The shots are currently on hold in several European countries over concerns about blood clots, though these may be coincidental and unrelated to the vaccine. 
 
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