Booster can keep severe symptoms from BA.4, BA.5 at bay: virologist

In a Facebook post on Monday, Dr Anan Jongkaewwattana shared lab results comparing the immunity three samples had against the two subvariants. The three samples cited were:

• Sample L: Two AstraZeneca jabs and a third jab of Pfizer vaccine received in April. Never contracted Covid-19.
• Sample P: Two AstraZeneca jabs and a third jab of Moderna vaccine received in March. The sample had been infected by the BA.2 subvariant earlier.
• Sample A: Two AstraZeneca jabs and a third jab of Pfizer. The sample was infected by the BA.2 subvariant after Songkran.

According to test results, Sample L had developed around 100 units of immunity against BA.2 but had lower immunity against BA.4 and BA.5 subvariants. However, Anan said, this may be enough to prevent severe symptoms.

The immunity levels of Sample P and Sample A came in at more than 2,100 and 3,700 units, respectively, and slightly lower against BA.4 and BA.5.

However, Anan said this experiment was too limited and had been conducted to test vaccine formulas in Thailand.

He said wanted to share this information informally to encourage people to get their booster shots, because BA.4 and BA.5 have been found to evade immunity. He added that immunity built from jabs or infection over three to four months should help prevent severe symptoms.