Sinopharm’s vaccine is effective against the highly contagious coronavirus Delta variant, a new study has found.
More than 95 per cent of the 282 people studied developed antibodies within two weeks of the second shot, said researchers at the University of Sri Jayewardenepura, Sri Lanka.
They said 81 per cent developed specific antibodies capable of neutralising the virus at levels similar to those seen after infection from Sars-CoV-2.
“Antibody responses to Delta variant and neutralising antibodies were similar to levels seen following natural infection,” they said.
However, antibody responses were lower in people over the age of 60, compared with those in the 20 to 39 age group, researchers said.
“Seroconversion rates and immunogenicity appear to be lower in older individuals,” the researchers wrote in a paper that is yet to be peer reviewed.
The researchers also compared immune responses to variants of the virus.
While the vaccine held up particularly well against Delta, the response was slightly lower compared with the original strain, according to researchers.
The vaccine also induced “robust T cell and memory B cell” responses, which are other crucial elements of the immune response, although "the magnitude of responses were less than those observed with some other vaccines”, the researchers wrote.
Sinopharm has developed two vaccines against the virus that causes Covid-19. The group tested the shot produced by the Chinese pharmaceutical company’s Beijing unit, which has been used widely in the UAE.
A leading US medical journal found that the two vaccines prevented symptomatic infections by 72.8 per cent and 78.1 per cent, largely in line with what the state-owned drug maker previously announced. The findings were reported in the May 26 Journal of the American Medical Association.
The World Health Organisation approved Sinopharm for emergency use in May this year.
A study in Abu Dhabi this year found the Sinopharm vaccine to be more than 90 per cent effective at reducing hospital admissions in those people infected with the coronavirus.
The Abu Dhabi Public Health Centre study found a significant decrease in the rate of new Covid-19 infections among people in the emirate who received a second dose of the vaccine.
Research has shown all vaccines, including the highly effective mRNAs, such as Pfizer-BioNTech, are slightly less effective against the Delta strain.
The Pfizer vaccine's lack of effectiveness may be particularly noticeable in those over the age of 50, according to researchers in Israel.
A monitoring team from Hebrew University in Jerusalem said on Tuesday that about 90 per cent of new confirmed cases in the over-50 age group were among people who had received both doses of the Pfizer vaccine.
Israel said this month that Pfizer was 64 per cent effective against infection from Delta, but 93 per cent effective against severe disease and hospital admission.
Johnson & Johnson’s vaccine is also less effective against Delta, compared with the original strain, according to early research by scientists at New York University.
That paper, which is yet to be peer reviewed, found that the levels of neutralising antibodies in a “significant fraction” of people were low.
By contrast, those who received mRNA vaccines still displayed antibodies with a “high level of cross neutralisation” to the variants.
The researchers said the results suggest those who received the Johnson & Johnson single-shot vaccine could benefit from a second immunisation against the virus to increase protection against new strains.