How soon after being infected with Covid-19 should a booster dose of vaccine?

With the spread of the Omicron variant around the world, many question whether a booster dose is needed if a person has recently contracted Covid-19.

In theory, the infection could produce antibodies called innate immunity. But can that replace vaccinations?

Artwork: Pharmaceutical-technology

Because booster doses can protect a person from serious illness, health authorities in many countries recommend that people get the shot soon after contracting Covid-19, but guidelines vary.

In Singapore, people are advised to get a booster shot 3 months after a negative test result, but in reality, it can be given after 28 days.

According to British health authorities, people who have just recovered from the disease need to wait at least 4 weeks before getting a booster shot. In Hong Kong, patients who recovered from Covid-19 did not need a third dose urgently.

The double protection in people who have been infected and then received the full 2 ​​doses is higher and longer lasting. This immunity remains strong one year after infection and more than 6 months after vaccination.

Having an infection can protect you for about 6 months, with immunity starting to wane after 4 to 6 months. A study by Johns Hopkins University showed that people who received two doses of the mRNA vaccine but subsequently became infected had longer immunity than those who were infected but not vaccinated.

“Some people with antibodies to SARS-CoV-2 can become infected after vaccination (breakthrough Covid-19 infection) or re-infection,” the US Centers for Disease Control and Prevention (CDC) informed.

In Hong Kong, the elderly are being vaccinated in droves as the fifth wave breaks out. Elderly people who have recovered from Covid-19 will receive a booster shot after 3 months.

Experience in South Africa, the first country hit by Omicron, shows that previous infection with other variants has little effect on Omicron.

In addition, a study in Qatar found that each Covid-19 infection was effective at protecting 90.2% against the Alpha variant, 85.7% against Beta, 92% against Delta but only 56% against Omicron.

In the UK, before November 2021, when Omicron had not appeared, reinfection accounted for only about 1% of Covid-19 cases. But the rate rose to about 10% after that.

Whether a person has been infected before or not, scientists suggest any approved and accessible vaccine is appropriate.

Apparently, even the mRNA vaccine – thought to be most effective against earlier variants of Covid-19 – could not completely prevent the transmission of the Omicron variant. But any approved vaccine reduces the severity of illness and death.

An Yen (According to SCMP)