The emergence and rise of BA.4 and BA.5 in South Africa and several other parts of the world have raised concerns among experts about a potential new wave of COVID-19. This is due to their ability to evade immunity.
South Africa is witnessing the onset of its fifth wave of COVID-19 as new cases surge once again in the country. According to the New York Times, the cause is two subvariants of Omicron – BA.4 and BA.5.
The BA.4 and BA.5 subvariants of the Omicron variant originated in South Africa. (Photo: REUTERS)
In the last week of April, the number of cases in South Africa tripled. Hospitalization rates also increased significantly. The rise is primarily concentrated in the provinces of Gauteng, Western Cape, and KwaZulu-Natal, occurring just months after the Omicron wave emerged in South Africa in the winter of 2021.
BA.4 and BA.5 are both branches of the original Omicron variant, first identified in November 2021. Previously, the WHO indicated that they were closely monitoring BA.4 and BA.5 because “they contain additional mutations that need further study to understand their impact on immune evasion.”
These two subvariants spread faster than BA.2 and are themselves more transmissible than the original Omicron strain. Scientists are still investigating whether they cause more severe illness in infected individuals.
In the United States, health officials have identified BA.4 and BA.5 at low levels, although another subvariant of Omicron, BA.2 and BA.2.12.1, is currently dominant. However, according to Fortune, every state in the U.S. has reported cases of BA.4 or BA.5, indicating a potential for rapid spread. The earliest sample of BA.4 was found in the U.S. on March 30, while BA.5 was identified on March 29.
According to findings by Professor Alex Sigal from the Africa Health Research Institute in South Africa, individuals who had previously been infected with Omicron BA.1 but were unvaccinated showed a reduction in neutralizing antibodies to 1/8 when exposed to BA.4 and BA.5. Meanwhile, those who had been vaccinated and had prior infections retained about 1/3 of their antibodies.
These results surprised Professor Sigal. The immune evasion capabilities of BA.4 and BA.5 exceeded his expectations, especially considering the changes from the original Omicron variant.
Professor Alex Sigal also warned that the BA.4 and BA.5 variants could trigger a new wave of COVID-19 due to their ability to evade antibodies, even in individuals who have been vaccinated or previously infected.
The symptoms in individuals infected with BA.4 and BA.5 remain quite similar to those of the original Omicron strain, such as fever, loss of smell, fatigue, and discomfort. Infected individuals do not exhibit respiratory distress—a symptom indicating severe illness. Therefore, experts conclude that it is less likely to be fatal.
