The jab is still our best bet – vaccines are likely to offer protection against Omicron

While the Covid-19 jab might not prevent infection, researchers have found clear and conclusive data that vaccines prevent severe disease, hospital admission and death.

Breakthrough infections – instances where fully vaccinated people contract the virus – have occurred but findings indicate that symptoms are not as severe compared with Covid-19 patients who are not vaccinated.

The advent of the new Omicron variant seems to have caused a spike in new cases. It has ushered in the so-called fourth wave sooner than monitors predicted. It is all the more reason for everyone to get the vaccine and boosters. It is likely to offer high levels of protection against the new variant. The more people who are vaccinated, the better we will be at collectively fighting the virus.

Building strong immunity limits virus growth and mutation

When the coronavirus first reached our shores it was expected to mutate over time and start with a high rate of infections. But it was also expected that as our immunity built up, it would limit the virus’s potency, spread and mutations.

This was the case with the 1918 flu pandemic. The world was able to fend off the virus because people collectively built up their immunity towards it. However, unlike the flu, Covid-19 has a faster-than-normal rate of change in critical parts of the virus. This seems to quicken transmission from one person to another.

Alarmingly, the coronavirus’s mutations affect the efficacy of the vaccine. For instance, when we assessed the AstraZeneca vaccine against the Beta variant, we saw a reduction in its efficacy.

Such findings are not expected so early in a pandemic. But few viruses have transmitted and mutated as rapidly as the coronavirus. What is expected is that it will not be fully eradicated. It will linger for some time.

The slow uptake of vaccinations is largely due to hesitancy caused by disinformation. Recent studies have shown that at least 30% of South Africans doubt the vaccine’s efficacy. Yet, something needs to be said of the difference between the rigorous efficacy process and effectiveness studies before we cast doubt on the vaccine.

In medical parlance, vaccine efficacy is determined through a clinical trial, in a controlled and regulated environment. The trials are randomised. The vaccine’s efficacy is then assessed in different cohorts – or designated groups of people – based on endpoints, or what the researchers want to see in the study. If the vaccine does what researchers expected it to do, the data are then passed on to the South African Health Products Regulatory Authority (Sahpra) for approval.

Thereafter, the effectiveness of the vaccine is assessed over time when it is publicly distributed. We then observe whether or not it is as efficacious as we had seen in the clinical trial.

Vaccine effectiveness kicks in about 14 days after receiving the jab. At this point the body starts making enough antibody titres – the presence and level of antibodies in the blood – to build up a decent degree of resistance against infection.

In South Africa, effectiveness has taken the course we expected. The vaccines that Sahpra had authorised and were later distributed countrywide had noticeably reduced disease severity and hospital admissions.

In studies that assess effectiveness in fully vaccinated people, it has been found that the antibody immunity wanes over time.

The time it takes for this to occur varies for each manufacturer. We have discovered that the Pfizer vaccine immunity loses its impact about eight months whereas Johnson & Johnson reaches that point anywhere between six to eight months.

At the point where antibody immunity has somewhat dwindled, there have been some early findings that show cellular immunity typically kicks in thereafter and lasts longer.

Cellular immunity should not be overlooked as it plays a critical role in fending off reinfection. It is expected that with time, as studies and information on vaccine effectiveness grow, the picture around cellular immunity will become clearer.

Dr Boitumelo Semete-Makokotlela.