Covid patients infected by the BA.5 Omicron sub-variant are now found in greater numbers than those with the BA.4 sub-variant. Both strains have been found to produce symptoms more severe than those caused by the BA.2 strain. Nonetheless, health authorities are asserting that booster shots of the vaccine help to prevent severe symptoms.
The Department of Medical Sciences (DMS) indicated it inspected 468 samples over the past week to determine the strain of the coronavirus in each. DMS Director-General Supakit Sirilak said 16 samples were from people who entered Thailand from abroad. 345 samples were from local patients who were without severe symptoms. 107 samples were from local patients who had severe symptoms or who died from COVID-19.
About 320 of all samples were of the BA.4 or BA.5 strains. Dr. Supakit said the two sub-variants have thus already established dominance. All of the randomly analyzed samples from international travelers entering Thailand involved the two sub-variants.
Dr. Supakit said speculation can be made about the two sub-variants producing more severe symptoms than the BA.2 strain. However, the degree of severity remains to be determined.
The DMS conducted a Plaque Reduction Neutralization Test to determine the immunity level that booster shot recipients have against the BA.4 and BA.5 sub-variants. The tests were done on samples collected from people who received two shots of either the Sinovac or AstraZeneca vaccines before receiving a booster. Booster shots used included the AstraZeneca vaccine and the Pfizer vaccine. Immunity levels against the BA.4 and BA.5 strains dropped significantly for all combinations of vaccines when compared to immunity against the BA.2 strain.
Dr. Supakit explained that Covid reinfection by the two sub-variants is possible in persons who have recently recovered from the BA.2 strain. He called on those who had their most recent Covid shot a long time ago to get a booster jab. This would improve immunity and reduce the severity of symptoms when an infection does occur. (NNT)
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