What should you know about the two new Omicron subvariants of the coronavirus?
The Centre for Medical Genomics at Ramathibodi Hospital says the number of patients found to have been infected by the BA.4 and BA.5 sub-variants of Omicron is rising in Thailand.
So far it has detected 49 cases of these two sub-variants, which may be able to circumvent antibodies produced by past infections or vaccination and could trigger a new wave of Covid-19.
These two sub-variants are responsible for a more-than 80% rise in hospitalisations of new Covid-19 infections in Europe.
That has underlined the need for Thailand to closely monitor how the presence of these new sub-lineages of the coronavirus that causes Covid-19 will affect the outbreak situation in the country. It comes amid plans to declare Covid-19 an endemic disease and lift more Covid-19 restrictions.
What are BA.4 and BA.5?
Prof Emeritus Wasun Chantratita, head of the Centre for Medical Genomics at Ramathibodi Hospital, said BA.4 and BA.5 are found to have up to 80 and 90 mutations respectively when compared with the first variant of the coronavirus that caused the first outbreak in Wuhan.
"These dramatic mutations come with the risk they will be more capable of evading immunity and trigger a new pandemic. However, whether they will cause severe disease remains to be seen through studies," he said.
Over 80% of newly infected patients in Portugal have needed hospitalisation, while the number of patient hospitalisations in South Africa has surged by 50% due to BA.4 and BA.5 infections, he said. Elsewhere in Europe, Austria, the Netherlands, France, Germany, Belgium, Spain, Italy and Denmark have now shared a similar rise in number of new Covid-19 patients requiring hospitalisation, he said.
How concerned should we be?
These strains are able to replicate well in the lungs of patients, unlike BA.1 and BA.21, the previous sub-variants of Omicron, which replicate their cells well only in the upper part of the respiratory system. In their case the risk of lung infections was considerably lower, he said.
Under the circumstances, certain European countries, particularly Portugal, have raised their Covid-19 alert, while the European disease-control body has announced that BA.4 and BA.5 require special surveillance, he said. The World Health Organisation (WHO), however, has yet to declare BA.4 and BA.5 a variant of concern.
What is the actual situation here?
Twenty-six cases of BA.5 and 23 cases of BA.4 have been detected in a random check conducted on new Covid-19 infections, which means the actual number of infections with BA.5 and BA.4 could be much higher, he said. These cases are believed to be imported ones, he said.
The number of patients infected with either BA.4 and BA.5 who suffered severe symptoms of infection remains rather low at the moment, based on the number of patients requiring hospitalisation, whch has increased only slightly, he said.
Close surveillance, however, is needed to keep track of how the two new sub-variants evolve, as these are still early days, he said.
Globally, BA.5 and BA.4 infections account for 17% and 8% respectively of all new cases, he said.
What about the risk of a new wave of Covid-19 in Thailand?
It's difficult to predict as this is a new disease and clear information must wait studies, he said.
As the WHO has said previously, Omicron won't be the last of Covid. His advice for fending off BA.4 and BA.5 is to avoid crowded areas, wear a face mask when necessary and get booster shots of the Covid-19 vaccine.