Achieving herd immunity against the COVID-19 may be unrealistic due to the mutations of the virus that causes it, South African experts have said, as they called for long-term vaccination strategies amid uncertainty about current vaccine efficacy.

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Many governments are targeting herd immunity, but it is unachievable in the same way it is unachievable for flu, said Professor Alex van den Heever, health and social security systems specialist of the University of the Witwatersrand (Wits) School of Governance. Van den Heever was speaking on an expert panel hosted by leading managed care provider and medical scheme administrator Agility Health.

The other panellists were virology expert Prof Sim Mayaphi and clinical pharmacology expert Dr Jacques Snyman. If we are vaccinated this year, this could mean we don't necessarily have immunity for the strains that emerge next year, said Snyman.

Various vaccines are targeting various sites of the virus. That particular antibody will only be effective as long as that part of the virus has not mutated. The Johnson & Johnson and Pfizer vaccines are only partially effective, but they reduce the likelihood and severity of illness, he added. Snyman said nobody knew whether the current vaccines would protect in the future. The next strain may not be affected by the antibodies we have vaccinated for. It is therefore likely that long-term vaccination strategies will be required, Snyman said.

Mayaphi, who is head of the Department of Medical Virology at the University of Pretoria, said the pandemic had caught everyone by surprise, as he called for better planning to prevent the next pandemic. Surveillance programmes are needed to look at the animal-human interface of viruses and the prevalence of viruses in animal hosts to see if we can predict these viruses being transmitted from host animals to humans. We already have many examples of this, including COVID-19, Mayaphi said.

Van der Heever also expressed concern about the late discovery that COVID-19 was an airborne virus. This poses the most extreme risk for a pandemic (as) it is the fastest (way in which) it could be transmitted. That is the one that is going to overrun testing and tracing - it's going to overrun border controls, he said. Data by Johns Hopkins University on Friday showed 3,431,904 deaths and 139,963,964 cases globally due to the coronavirus.