The two-dose vaccine's ineffective prevention of the more transmissible virus variant led to official seeking better options—and broader outcomes.
The AstraZeneca coronavirus 2019 (COVID-19) vaccine will be at least temporarily removed from the South Africa vaccination program, after research showed the two-dose adenovirus vaccine is not as effective as hoped against the regionally-borne 501Y.V2 variant.
The decision, made public by the country’s health officials this weekend, is a concerning development in the ongoing global efforts to vaccinate against the pandemic while more transmissible variants, including the South Africa strain, spread further across the world.
The 501Y.V2 variant has been linked to significant increases in South Africa COVID-19 cases at the end of 2020, and has been observed as spreading throughout countries including the US in early 2021.
Because of its greater transmissibility, investigators recently reported that the vaccine developed by AstraZeneca and the University of Oxford was only linked to 22% lowered risk of mild-to-moderate COVID-19 development in the South Africa region. This rate pales in comparison to the approximate 75% efficacy associated with the vaccine prior to the new variant circulation.
Though investigators were unable to confirm statistical significance of this new finding, the vaccine’s observed drop below the threshold of ≥50% efficacy warranted the decision to forego administration of the two-dose option for the time being.
In the day prior to the decision, AstraZeneca leadership expressed belief the vaccine could protect against severe COVID-19, and that the company was already adapting its components to address the South Africa variant.
But this shortcoming leads to health official reconsidering the entire strategy of COVID-19 vaccination rollout and prioritization. In one way, lead South Africa AstraZeneca trial investigator Professor Shabir Madhi said in a statement, it requires officials to “recalibrate our expectations of COVID-19 vaccines.”
Though this current research did not observe the vaccine’s benefit versus severe COVID-19 cases due to the younger, less at-risk patient population, investigators suggested individuals to have received the first dose should possible be offered another effective prophylaxis, or a booster based on the variant’s sequencing.
Madhi echoed that the vaccine should be used in a targeted group to interpret hospitalization risks before being at all rolled out to the region burdened by the variant.
Time is of the essence to full interpret the AstraZeneca vaccine: in its effort to begin vaccinating two-thirds of its population (40 million people), the country had received 1 million doses of the vaccine under question. Plans to administer doses to healthcare workers starting Monday will be delayed, in order to provide them mRNA vaccines from Pfizer and BioNTech, as well as Moderna.
As uncertainty clouds the utility of an already available vaccine at a time when a more transmissible form of the virus is spreading, the country’s officials remain committed to interpreting basic value of the two-dose shot: could it help keep people out of the hospital?
While that answer is sought, another major country’s immunization strategy is partially compromised.