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BEIJING (REUTERS) - Antibodies triggered by Sinovac Biotech’s Covid-19 vaccine declined below a key threshold from around six months after a second dose for most recipients, but a third shot had a strong booster effect, a lab study showed.

Chinese researchers reported the findings from a study of blood samples from healthy adults aged between 18 and 59 in a paper published on Sunday (July 25), which has not been peer reviewed.

Among participants who received two doses, two or four weeks apart, only 16.9 per cent and 35.2 per cent respectively still had neutralising antibodies above what researchers regard as a detectable threshold level six months after the second shot, the paper said.


Those readings was based on data from two cohorts involving more than 50 participants each, while the study gave third doses to a total of 540 participants.

Researchers said it was unclear how the decrease in antibodies would affect the shot’s effectiveness, since scientists have yet to figure out precisely the threshold of antibody levels for a vaccine to be able to prevent the disease.

Apart from durable antibodies, other components in humans immune systems such as T cells and B cell memory elicited by the vaccine may also contribute to protection, researchers involved in the study said, although the study did not provide data on those factors.


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“In the short-to-medium term, ensuring more people complete the current two-dose schedule of CoronaVac (Sinovac’s vaccine) should be the priority,” the paper said.

Participants in some cohorts who received a third dose of the Sinovac shot about six months after the second showed around a 3-5 fold increase in antibody levels after a further 28 days, compared with the levels seen four weeks after the second shot.

As of end-June, Sinovac has delivered more than 1 billion doses of the vaccine, a major vaccination tool in China, Brazil, Indonesia and Chile.

Other Covid-19 vaccine makers are seeking to get authorisation for booster shots. Pfizer and partner BioNTech said earlier this month they had planned to ask US and European regulators within weeks to authorise a booster dose of its Covid-19 vaccine, based on evidence of greater risk of infection six months after inoculation and the spread of the highly contagious Delta variant.

Siti Nadia Tarmizi, a senior health ministry official in Indonesia, told Reuters on Tuesday (July 27) that clinical data from the country showed the reduced antibody level is still enough to provide protection, without providing details.

She said the immunisation advisory board recommends a booster vaccination 12 months after the second dose.

Indonesia has started giving booster shots produced by Moderna to medical workers this month, including those who had received Sinovac doses.

Philippines’ Health Secretary Francisco Duque said on Tuesday that there is no recommendation yet from the country’s vaccine expert panel on giving a booster shot, but experts are discussing the possibility.

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Turkey has already started offering a third dose from either Sinovac or Pfizer to some people who have got Sinovac shots.

The research paper on Sinovac’s vaccine said that 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.

The study was conducted by researchers at disease control authorities in Jiangsu province, Sinovac, and other Chinese institutions.

Dont read ST...
Read CNA news, still more balanced view.
The readers are not mainly dafts.

REUTERS news always add in spice. Nowadays most of the reputable news outlets are biased even our local news outlets.

The memory on how to fight the virus is still there.

Israel having Sinovac???

(28-07-2021, 08:34 AM)RiseofAsia Wrote: [ -> ]Dont read ST...
Read CNA news, still more balanced view.
The readers are not mainly dafts.

https://www.channelnewsasia.com/news/asi...y-15301994

BEIJING: Antibodies triggered by Sinovac'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 to 59 in a paper published on Sunday (Jul 25), which has not been peer reviewed.

We learned about Kung fu fighting but we had forgotten how to fight.

The Forgotten Fight of Bruce Lee
https://www.youtube.com/watch?v=BG-E7SuNT1o

Going by real data of infected here. Looks like P&M fade even faster.. like 3 mths boliao

sinovac better than nothing….

(28-07-2021, 11:10 AM)pervertosan Wrote: [ -> ]sinovac better than nothing….

Yupe .... go for the one you feel comfortable with. Even 6mths is real, you are protected for 6mths
Gib you rep

People still dun understand. It is better to go for a vaccination method that is proven to cause no harm albeit with shorter protection period than one whose impact is uncertain.

(28-07-2021, 08:50 AM)cityhantam Wrote: [ -> ]Israel having Sinovac???

China so evil? Forced Israel to use Sinovac vaccine???

(28-07-2021, 11:10 AM)pervertosan Wrote: [ -> ]sinovac better than nothing….

Israelis should thank pervertosan for exposing "evilness" of China in forcing them to take useless Sinovac vaccine!

https://www.timesofisrael.com/as-israel-...-6-months/

Israeli health workers vaccinated with the Pfizer shot were still showing very high levels of antibodies six months after their shots, the Kan public broadcaster reported Tuesday.

The report, based on serological studies conducted by Israel’s four health maintenance organizations on health care workers, who were the first Israelis to get the shots in December, found that most had antibody levels above 700. The report said a level of 150 was needed to be considered protected.

These people were given Sinovac vaccine???

So jialat???

Any non fadable vaccine.

https://www.channelnewsasia.com/news/wor...s-15303112

A total of 114 doctors died during July 1-17, the highest number reported for any period of similar length and more than 20 per cent of the 545 total doctor deaths from Covid-19 since the beginning of the pandemic, officials from Indonesia's doctors association (IDI) said during a virtual news conference.

maybe antibodies too low.

https://www.timesofisrael.com/serious-co...-3-months/

Aiya, all same same, P&M also need booster shots.

39% is too low. double masks are better

(28-07-2021, 08:34 AM)RiseofAsia Wrote: [ -> ]Dont read ST...
Read CNA news, still more balanced view.
The readers are not mainly dafts.

Read CGTN or China Daily News?

(28-07-2021, 11:49 AM)cityhantam Wrote: [ -> ]

https://www.timesofisrael.com/serious-co...-3-months/

Check and check everyday here.. no such announcement.. anyway peoplel will still quote this next year 

https://www.gov.il/en/departments/news?O...af928c19c0&limit=10&skip=0

(28-07-2021, 01:34 PM)Justice Wrote: [ -> ]

(28-07-2021, 11:49 AM)cityhantam Wrote: [ -> ]

https://www.timesofisrael.com/serious-co...-3-months/

Check and check everyday here.. no such announcement.. anyway peoplel will still quote this next year 

https://www.gov.il/en/departments/news?O...af928c19c0&limit=10&skip=0

The Times of Israel didn't inform you? 

This whole thing about vaccinate losing antibodies after a certain month is something puzzling to me. Doesn't restrict to only sinovac, every vaccine for covid it seems.

By right the vaccine teaches your T cells to recognise the virus so your body can create the antibodies for it. Why for covid the antibodies or your T cell doesnt work rite??

(28-07-2021, 01:54 PM)cityhantam Wrote: [ -> ]

(28-07-2021, 01:34 PM)Justice Wrote: [ -> ]Check and check everyday here.. no such announcement.. anyway peoplel will still quote this next year 

https://www.gov.il/en/departments/news?O...af928c19c0&limit=10&skip=0

The Times of Israel didn't inform you? 

You believe such important news that will affect national vaccination agenda in the Straits Times,  Zao Pao etc more than in  MOH news?  You sure no parqua news ?

(28-07-2021, 02:35 PM)Sticw Wrote: [ -> ]This whole thing about vaccinate losing antibodies after a certain month is something puzzling to me. Doesn't restrict to only sinovac, every vaccine for covid it seems.

By right the vaccine teaches your T cells to recognise the virus so your body can create the antibodies for it. Why for covid the antibodies or your T cell doesnt work rite??

Because of mutation. Even for flu jabs, you need yearly boosters because the virus mutate and the body don't know how to react fast enough to create antibodies. 

Whether is mRNA or non-mRNA, same issues. 

So there is no need to argue liao. All same but inactivated virus type of vacc like Sinovac is safer with fewer and milder side effects so far.

As long as it helps to protect against severe illness, they shouldn't be any discrimination. If anything, should discriminate against mRNA due to the unknown longer term adverse effects. 

I think in 10 years if there are sufficient data to prove that mRNA is indeed safe, then we should make it compulsory. A big IF ....

Report from Reuters.

Pfizer director, James C. Smith is President, CEO and director of Thomsen Reuters Corporation.

Reuters reports have consistently slammed Chinese vaccines.

Read Reuters reports on Chinese vaccines with a pinch of salt.