Understanding the Effectiveness of Vaccines Against the South African Variant of COVID-19

The emergence of the South African variant of the SARS-CoV-2 virus (also known as B.1.351) has raised concerns about the effectiveness of currently available vaccines. This variant has been noted for its increased resistance to certain vaccines, particularly AstraZeneca's, leading to questions about how well existing vaccines can protect against it.

Resistance vs. Immunity

It is important to clarify the distinction between resistance and immunity. While some people may have a partial immune response to the AstraZeneca vaccine when exposed to the South African variant, developing full immunity through vaccination is not guaranteed. As mentioned, nine out of ten people vaccinated against this variant may still experience symptomatic illness if exposed. However, data indicates that the risk of severe disease and death is significantly lower in vaccinated individuals compared to those who are unvaccinated.

Partial Efficacy and Compromises

Studies have shown that the contemporary vaccines do work against the South African variant to some degree, but they are somewhat less effective than they are against the original or wild-type virus. This is due to the mutations in the viral spike protein, which can affect the immune response.

For instance, the Johnson Johnson vaccine has been found to have an efficacy rate of around 60% against mild to moderate illness caused by the South African variant. Similarly, the Moderna and Pfizer vaccines maintain efficacy rates of around 80%. These figures suggest that while the vaccines are not as effective as they are against other variants, they still offer substantial protection against severe disease and hospitalization.

Limited Evidence and In Vitro Studies

While the available data from studies such as Johnson Johnson and Novavax phase 3 trials conducted in South Africa indicate a noticeable reduction in efficacy, the evidence is still limited. In vitro studies of other vaccines have further revealed that these vaccines may have a degree of antibody evasion, which can reduce their effectiveness against the South African variant.

The limited evidence available suggests that the current vaccines may offer less protection against mild-to-moderate infections caused by the South African variant. However, they should still be effective in preventing serious illness and hospitalization. Some researchers believe that a third dose or a mixed vaccine strategy may enhance protection until more specific vaccines are developed.

Current Pharmaceutical Response

As of the latest data, the Western vaccines, except for AstraZeneca, have maintained reasonable effectiveness against the South African variant. However, the efficacy of AstraZeneca's vaccine drops significantly against the mild-to-moderate disease. Despite this, some believe that it may still offer some protection against severe disease, although the lack of data from its phase 3 trials in South Africa makes it difficult to ascertain its full impact.

Overall, while the South African variant poses challenges, the current vaccines still provide considerable protection against severe disease and hospitalization. Ongoing research and vaccine development will continue to address these concerns and improve protection against the variant.