Less potent natural immunity to new Omicron strains in South Africa as fifth wave looms – Magnetic Media
By Dana Malcolm
#Africa, May 19, 2022 – South Africa is experiencing a massive covid surge with cases jumping 50% in just 24 hours on May 5. 9,757 new cases were reported on the 5th, 3,587 more positives than the 6,170 recorded the day before. For context, on April 5, a month earlier, 1538 new infections were recorded.
Since that 50% increase on May 5, new daily infections have consistently exceeded 2,900, reaching 10,017 on May 11. South Africa recorded over 86,000 new cases and over 550 deaths between May 5 and May 16 in less than 2 weeks.
Vaccination coverage in South Africa is just under 50% with only 35 million people fully immunized out of a population of over 59 million.
Shabir Mahdi, a scientist leading vaccine trials in the country, had suggested that natural immunity was what helped reduce hospitalizations when omicron first appeared in the country.
However, the latter increase is due to the BA.4 and BA.5 Omicron subvariants, which may be more adept at evading natural immunity.
In a study by the Africa Health Research Institute, blood samples from people infected with omicron but not vaccinated, when tested against BA.4 and BA.5, neutralizing antibodies that fight Covid were eight times lower. In people who contracted omicron and were vaccinated, it was three times lower.
The study has not yet been peer reviewed, but the researchers state: “The low levels of absolute neutralization for BA.4 and BA.5, particularly in the unvaccinated group, are unlikely to protect well against symptomatic infection.
“This may indicate that … BA.4 and BA.5 have the potential to lead to a new wave of infection.”
This study was carried out in January when the variants were first detected.
When the fourth wave powered by Omicron hit South Africa in 2021 cases in the United States, Canada and parts of Europe soon followed. BA.4 and .5 have been detected in the United States, Canada, China and parts of Europe.
On May 12, the BA.4 and .5 variants were both upgraded to worrying variants by the European Center for Disease Control.
The ECDC states that the variants of concern are those for which “clear evidence is available indicating a significant impact on transmissibility, severity and/or immunity which is likely to have an impact on the epidemiological situation in the EU /EEE”.
Possible spike in cases comes a year and five months since the world’s first COVID vaccines were given in the UK and US, a year and four months since the first vaccine was given in the Turks and Caicos Islands .
Although boosters have been available in many countries, worldwide booster campaigns have not been as effective as the initial vaccination campaigns. Without the extended protection of recalls, many more people could remain vulnerable to this growing wave of BA.4 or BA.5 vaccines.