Antibodies triggered by Sinovac Biotech’s COVID-19 vaccine decline below a key threshold from around six months after a second dose for most recipients, although a third shot could have a strong boosting effect, according to a lab study.
Chinese researchers reported the findings from a study of blood samples from healthy adults aged between 18-59 in a paper published on Sunday, which has not been peer reviewed.
Read the latest updates in our dedicated coronavirus section.
For participants receiving two doses, two or four weeks apart, only 16.9 percent and 35.2 percent respectively still had a level of neutralizing antibodies above the threshold six months after the second dose, the paper said.
For the latest headlines, follow our Google News channel online or via the app.
Those readings were based on data from two cohorts involving more than 50 participants each, while the study gave third doses to a total of 540 participants.
When participants in some cohorts were given a third dose, about six months after the second, neutralizing antibody levels after a further 28 days had increased around three to five fold from the levels seen four weeks after the second dose, the study showed.
The study was conducted by researchers at disease control authorities in Jiangsu province, Sinovac, and other Chinese institutions.
Researchers cautioned the study did not test the antibodies’ effect against more transmissible variants, and that further research was needed to assess antibody duration after a third shot.
China says ‘shocked’ by WHO plan for second COVID-19 origins study
Thai health workers vaccinated against COVID-19 with Sinovac to receive booster
Singapore omits Sinovac jabs from COVID-19 vaccination tally
China logs 76 new COVID-19 cases, highest daily rise since JanuaryChina on Monday reported 76 new coronavirus cases, the highest daily rise since January, including 40 domestic transmissions prompting authorities to ... Coronavirus
China to conduct mass COVID-19 testing in county near Myanmar: GovernmentEveryone in a county in China’s southwest near Myanmar will be tested for the coronavirus following a spike in infections, the government announced ... Coronavirus
China says ‘shocked’ by WHO plan for second COVID-19 origins studyChina rejected on Thursday a World Health Organization (WHO) plan for a second phase of an investigation into the origin of the coronavirus, which ... Coronavirus
Thai health workers vaccinated against COVID-19 with Sinovac to receive boosterA nighttime curfew and other new coronavirus restrictions began Monday in Thailand’s capital and several other provinces, as health officials ... Coronavirus
Singapore omits Sinovac jabs from COVID-19 vaccination tallyPeople who received Sinovac Biotech shots are excluded from Singapore’s count of total vaccinations against COVID-19, officials in the city state said ... Coronavirus