Updated: February 24, 2021
Experts from the World Health Organization on Wednesday recommended the continued use of AstraZeneca vaccine despite the South Africa setback.
A recent studied showed that the vaccine developed by AstraZeneca and Oxford University was not very effective against a new variant of coronavirus first detected in South Africa. But the vaccine remained about 63 percent effective against the old strain of the virus, SARS-CoV-2.
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The Strategic Advisory Group of Experts (SAGE) on Immunization at its extraordinary meeting on February 8, 2021, said its “interim recommendations” were that more studies would be needed, but that the vaccine was safe to use.
SAGE wrote: “The AZD1222 vaccine against COVID-19 has an efficacy of 63.09% (95% CI 51.81; 71.73) against symptomatic SARS-CoV-2 infection, as shown by the primary analysis of data irrespective of interdose interval (data cut 7 December 2020) from trial participants in the United Kingdom, Brazil and South Africa who received 2 standard doses.
“Vaccine efficacy tended to be higher when the interval between doses was longer. This, together with the finding of higher antibody levels with increasing interdose interval, supports the conclusion that longer dose intervals within the 4–12 weeks range are associated with greater vaccine efficacy.
“No vaccinated persons were hospitalized as from 22 days after dose 1, compared with 14 unvaccinated persons who were hospitalized for COVID-19 in the same time frame. At the time of analysis, the median follow-up time after the second dose was 80 days.”
WHO recommended the following post-authorization monitoring activities and research.
Safety surveillance and monitoring:
− serious adverse events, anaphylaxis and other serious allergic reactions, Bell`s palsy, transverse myelitis, cases of multisystem inflammatory syndrome following vaccination, cases of COVID-19 following vaccination that result in hospitalization or death;
− background rates of AESIs, maternal and neonatal outcomes, and mortality in groups prioritized for vaccination.
− vaccine effectiveness in older persons;
− vaccine effectiveness in relation to time interval between the first and second dose;
− vaccine effectiveness in relation to new virus variants;
− vaccine effectiveness over time and whether protection can be prolonged by booster doses;
− booster studies with heterologous vaccines;
− studies to investigate whether this vaccine reduces SARS-CoV-2 transmission and viral shedding;
− assessment and reporting of breakthrough infections and virus sequence information;
− head-to-head studies with other vaccines on extent and duration of immunity using standardized neutralization, T-cell and mucosal immunity assays.
− prospective studies on the safety of AZD1222 vaccine in pregnant and lactating women;
− randomized controlled trials on efficacy and safety of vaccination in persons below the age of 18 years;
− safety data on vaccination in immunocompromised persons, including persons living with HIV and persons with autoimmune disease.
− immunogenicity and safety studies of co-administration with other vaccines, including influenza and pneumococcal vaccines, to adults and older persons;
− safety, immunogenicity, and impact of a delayed second dose, as currently implemented by certain countries;
− interchangeability and “mix and match” studies within and across COVID-19 vaccine platforms;
− stability of vaccine under alternative cold-chain distribution and storage conditions.
− global surveillance of virus evolution and the impact of virus variants on vaccine effectiveness to support update of vaccines;
− Modelling to determine the trade-offs for the use of vaccines with reduced effectiveness against emergent variants;
− Booster studies with updated vaccine formulations.