Coronavirus: recovered Hongkongers should still get three shots of Covid-19 vaccine, says expert
- Studies show reinfection in recovered patients may increase risk of death, admission to hospital and complications in different organs
- A 22-month-old girl infected with Covid-19 dies on the day government advisers recommend vaccination age be lowered to 6 months
William Chui Chun-ming, president of the Society of Hospital Pharmacists, said in an interview on Monday that neutralising antibodies produced by Covid-19 infection could not replace the ones from vaccines, and were not enough to tackle Omicron variants BA4 and BA5.
He said studies had shown that reinfection in recovered patients might increase the risk of death, admission to hospital, and complications in different organs.
“People think that being infected is some sort of ‘windfall’ because they don’t need to get vaccinated temporarily and have exemption from mandatory testing,” Chui said, stressing Omicron strains were able to evade immunity, resulting in potential reinfection.
According to the city’s vaccination guidelines, adults aged 18 to 59 with higher risk or personal need and who have received two doses of vaccine before catching the virus, may choose to receive their third shot six months after infection. He said the window could be shortened to enhance immunity.
“The neutralising antibody level from infection will go down after three months, while the antibody level by vaccination can last for six months, the recovered individuals should take the required dose without waiting [for a second-generation vaccine].”
Chui said some fifth-wave patients were reinfected, without revealing any numbers, warning severe outcomes might be more common with Omicron variants.
He cited a study from the United States that used the health records of more than 5.64 million people provided by the US Department of Veterans Affairs. The study population was broken down into about 250,000 participants with at least one documented Covid-19 infection.