A fifth wave of Covid has hit South Africa with the sub-variants of Omicron BA.4 and BA.5. But the disease seems to become progressively less severe, even as its contagiousness increases. “With the BA.4 and BA.5 variants of Omicron, South Africa has entered the fifth wave, which is very different from that caused by Omicron BA.1,” Tulio de Oliveira, professor of bioinformatics at the University of KwaZulu, told The Wire. -Natal and Stellenbosch. According to de Oliveira, infections “are increasing”, while hospitalizations and deaths are “very low”. In fact, in South Africa there are about 300 people hospitalized in intensive care and the hospital beds reserved for Covid patients are 90% empty.
Omicron, the South Africa case
Also in The Wire, de Oliveira recalled that “all nine provinces of the country have detected the presence of BA.4 and BA.5”. And that these variants are contagious especially for those who are not vaccinated and have fallen ill with a previous mutation, while those who are fully vaccinated can count on sufficient immunization. Furthermore, according to de Oliveira, many of the people infected with BA.4 and BA.5 remain asymptomatic and when they do have symptoms these are very mild. These sub-variants, therefore, are more infectious but the disease they cause is relatively mild: “One of the reasons why the disease is becoming less severe is that the immunity of the population is increased, both from previous infections and vaccinations.”
Sub-variants and contagiousness
Globally – reports WHO – BA.4 and BA.5 represent respectively 0.5% and 0.4% of all circulating variants of Sars-CoV-2. According to preliminary investigations, the two sub-variants show “a higher growth rate than other variants such as Delta”. WHO highlighted that in South Africa BA.4 and BA.5 appear to lead an increase in the number of Covid-19 cases, accounting for 89% and 7% respectively of the sequences uploaded to Gisaid in mid-May. Since the end of April, the country has also recorded “a moderate increase in hospital admissions, although significantly lower – specifies the United Nations health agency – than that observed with the appearance of Omicron at the end of 2021”. WHO also reports «first indications of an increase in the number of cases in Portugal, which has recently confirmed the spread of BA.5. The hospitalizations “in the medical area” and in intensive care remain “stable” in the country in mid-May. In the US, however, the prevalence of BA.2.12.1 is 48%: “Cases and hospitalizations have been increasing since April, with an increase of 33% and 19% respectively during the week from 9 to 15 May, compared to the previous one “.
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