AstraZeneca COVID-19 Vaccine Shows Higher Immune Response With Longer Gap, Third Booster Dose

A sub-analysis from the Oxford-led COV001 and COV002 trials with AstraZeneca Plc AZN COVID-19 vaccine induced strong immune responses following a prolonged second dose interval to 45 weeks (10 months) or following a third boosting dose.
The researchers were also able to show that a booster given more than six months after the second dose induced a strong response and increased activity against variants.
The study found that antibodies induced after a single dose survived to some extent after one year. Still, after 180 days, the levels were half those seen at the 28-day peak.
However, a second dose increased antibody levels between four- and 18-fold by one month after the shot.
Thirty participants who only received a single dose in the trial were given a second one about ten months after the first.
An additional 90 participants from those studies received the third dose in March this year.
Higher levels of neutralizing antibodies against the alpha, beta, and delta variants of SARS-CoV-2 were also shown after a third dose than after the second one.
Oxford and Astra have also started another trial to test a variant vaccine adapted to better protect against the beta variant. The late-stage trial is expected to recruit about 2,250 participants.
Price Action: AZN shares are up 1.36% at $60.16 during the market session on the last check Monday.