A third booster dose of a COVID-19 vaccine from either AstraZeneca Plc AZN, Pfizer Inc PFE - BioNTech SE BNTX, or Johnson & Johnson JNJ increases antibody levels significantly in those who have previously received two doses of Sinovac Biotech Ltd SVA CoronaVac.

• According to the study, CoronaVac received the strongest boost from a viral vector or RNA shot, including against the Delta and Omicron coronavirus variants.
• "This study provides important options for policymakers in the many countries where inactivated vaccines ... have been used," said Andrew Pollard, director of the Oxford Vaccine Group and study lead.
• Related: Sinovac's COVID-19 Vaccine With Pfizer Booster Less Effective Against Omicron.
• However, another study in December found that Sinovac's two-dose shot followed by a booster dose of Pfizer-BioNTech's vaccine showed a lower immune response against the Omicron variant than other strains. 
• The third dose of CoronaVac also increased antibodies, but the results were better when a different vaccine was used, according to the latest study that included 1,240 volunteers in Brazil.
• Antibody levels were low before delivery of the booster doses, with only 20.4% of adults aged 18-60 and 8.9% of adults aged over 60 having detectable levels of neutralizing antibodies. 
• These were seen to significantly increase across every booster vaccine regimen, across all groups, 28 days post-vaccination.
• Price Action: SVA shares were trading at $6.47 during the market session on the last check Monday.