Antibodies from Sinovac's COVID-19 shot fade after about 6 months, booster helps - study

[snoop1130]

FILE PHOTO: Bottles of the Sinovac vaccine are seen at a hospital, as Indonesia drives mass vaccination for the coronavirus disease (COVID-19), in Jakarta, Indonesia, January 21, 2021. REUTERS/Willy Kurniawan

 

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, although a third shot had a strong booster 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findings from a study of blood samples from healthy adults aged between 18-59 in a paper published on Sunday, which has not been peer reviewed.

 

Among participants who received two doses, two or four weeks apart, only 16.9% and 35.2% 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 were based on data from two cohorts involving more than 50 participants each, while the study gave third doses of the vaccine or placebo 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.

 

"In the short-to-medium term, ensuring more people complete the current two-dose schedule of CoronaVac should be the priority," the paper said.

 

Indonesia and Thailand have already agreed to give a third shot from Moderna and Pfizer respectively for some people who are fully vaccinated with the Sinovac vaccine, amid concerns over its effectiveness against the more transmissible Delta variant of the coronavirus.

 

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

 

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.

 

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

 

The study also said that 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.

 

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.

 

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

 

-- © Copyright Reuters 2021-07-27

 

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[Scrotobike]

When were the majority of (single dose) sinovac given? What is the effectiveness against the Delta variant over time? Month by month?

[internationalism]

the last week's research said it was only 4 weeks, when this vax became ineffective 

[arick]

Why is the second dose given so soon. What happens if you wait 8 weeks like the other vaccines. Maybe Panda is in a hurry. 

[TheFishman1]

 Thailand  orders so much vaccine from  China it seems like it’s the least effective and the effects are very short term and protection against the virus why did Thailand wait so long to order the vaccines that work corruption at every level not caring about the citizens or the people living in this country I would say they should be ashamed but I think that it’s just their way of doing business no shame TAT 

[howbri]

I will never inject ANYTHING from China into my body.

[bert bloggs]

My wife asked me last night why doesnt any country ban anything Chinese and why dont they prosecute them for giving the world covid?  I said because we have come to rely on their cheap <deleted> for so long .frightening isnt it

[oldcpu]

So its a study, that is NOT peer reviewed, that states its unclear if the noted antibody decrease affects the effectiveness, but they then go on to say they can increase the antibodies by a 3rd jab of Sinovac.    So what?

 

Not what I would call definitive that the 3rd jab really needed, nor if 3rd jab should be Sinovac or AstraZeneca, or an mRNA ??  ????   ... hopefully as time goes by, with millions already vaccinated around the world with Sinovac, that better information/studies will be forth coming - than a news grabbing article that offers very little. ????

[Rimmer]

A post denigrating and calling Chinese vaccines junk has been removed.

Whilst it may be less effective in certain cases ie Delta strain it is by no means useless.

At the end of the day this is a Thai government sponsored vaccine and the forum and or yourself can get in trouble for comments like this so stop it.

[MrJ2U]

Thats bad news.

 

Its already established the efficiency rate is very low.

 

On top of this there out of Oxygen tanks the day after the government said they have ample supply.

 

I can feel the anger growing everyday against the people running this sh** show.

 

 

 

[cormanr7]

It is not just Sinovac that results in rapidly waning antibody levels. This recent article in the Lancet describes rapidly waning total antibody levels after full (i.e. two doses plus a 2 week period) vaccination with either Pfizer or AZ. The decline started after some six weeks and by 10 weeks had reached 50%. You have to read the article (https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)01642-1/fulltext) yourself to see some of the limitations of the study.  Authors note, for instance that (quote) 'the clinical implications of waning antibody levels are not yet clear and it remains crucial to establish S-antibody thresholds associated with protection against infection and disease.'

 

The study also confirms that Pfizer gives ca 4-fold higher antibody levels than AZ, but in a comment on the article it is noted that (quote from https://www.sciencemediacentre.org/expert-reaction-to-research-letter-looking-at-spike-antibody-level-waning-after-second-doses-of-the-pfizer-biontech-and-oxford-astrazeneca-vaccines/) 'mRNA vaccines such as the Pfizer/BioNtech vaccine are designed to induce high concentrations of antibodies. Viral vectored vaccines (such as the Oxford AstraZeneca vaccine) tend to induce lower antibody response but stronger T cell responses. The differences in antibody concentrations induced by the two vaccines is thus not surprising and not a cause for concern.

“However, emerging evidence suggests that antibodies are particularly important for blocking infection and preventing onward transmission of the virus whereas T cells may be particularly relevant for preventing severe disease and death. Maintaining sufficient antibody concentrations to reduce transmission will be important to limit the amount of circulating virus but maybe less important for protection against severe disease.'

 

 

 

[Rimmer]

Troll post removed

[samtab]

ALL vaccine antibodies fade after 6 months ! what a ridiculous post one more time...

 

[samtab]

5 hours ago, TheFishman1 said:

 Thailand  orders so much vaccine from  China it seems like it’s the least effective and the effects are very short term and protection against the virus why did Thailand wait so long to order the vaccines that work corruption at every level not caring about the citizens or the people living in this country I would say they should be ashamed but I think that it’s just their way of doing business no shame TAT 

don't say that ! I have read on this forum that this vaccine is sooo gooood, this is why the thai government uses it !

 

????

 

 

[MrJ2U]

8 hours ago, cormanr7 said:

It is not just Sinovac that results in rapidly waning antibody levels. This recent article in the Lancet describes rapidly waning total antibody levels after full (i.e. two doses plus a 2 week period) vaccination with either Pfizer or AZ. The decline started after some six weeks and by 10 weeks had reached 50%. You have to read the article (https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)01642-1/fulltext) yourself to see some of the limitations of the study.  Authors note, for instance that (quote) 'the clinical implications of waning antibody levels are not yet clear and it remains crucial to establish S-antibody thresholds associated with protection against infection and disease.'

 

The study also confirms that Pfizer gives ca 4-fold higher antibody levels than AZ, but in a comment on the article it is noted that (quote from https://www.sciencemediacentre.org/expert-reaction-to-research-letter-looking-at-spike-antibody-level-waning-after-second-doses-of-the-pfizer-biontech-and-oxford-astrazeneca-vaccines/) 'mRNA vaccines such as the Pfizer/BioNtech vaccine are designed to induce high concentrations of antibodies. Viral vectored vaccines (such as the Oxford AstraZeneca vaccine) tend to induce lower antibody response but stronger T cell responses. The differences in antibody concentrations induced by the two vaccines is thus not surprising and not a cause for concern.

“However, emerging evidence suggests that antibodies are particularly important for blocking infection and preventing onward transmission of the virus whereas T cells may be particularly relevant for preventing severe disease and death. Maintaining sufficient antibody concentrations to reduce transmission will be important to limit the amount of circulating virus but maybe less important for protection against severe disease.'

 

 

 

Sinovac has a very low effeciancy rate to begin with.  For it to drop by 45% in 6 months is alarming.  

[KhaoNiaw]

12 minutes ago, MrJ2U said:

Sinovac has a very low effeciancy rate to begin with.  For it to drop by 45% in 6 months is alarming.  

You're confusing efficacy and antibodies. 

[MrJ2U]

3 minutes ago, KhaoNiaw said:

You're confusing efficacy and antibodies. 

Won't be the last time.

 

I would think that less antibodies would result in lower effeciancy.

[KhaoNiaw]

Just now, MrJ2U said:

Won't be the last time.

 

I would think that less antibodies would result in lower effeciancy.

Not necessarily.

[MrJ2U]

1 minute ago, KhaoNiaw said:

Not necessarily.

Ok

[placeholder]

22 hours ago, internationalism said:

the last week's research said it was only 4 weeks, when this vax became ineffective 

The writer of the article may have said something like that (but I don't think so) but effectiveness in regards to a vaccine has to do with how well it performs in real world conditions. How welll it actually prevents infections and also how potent it os against serious symptoms and death.

[placeholder]

11 hours ago, bert bloggs said:

My wife asked me last night why doesnt any country ban anything Chinese and why dont they prosecute them for giving the world covid?  I said because we have come to rely on their cheap <deleted> for so long .frightening isnt it

I wish iphones were cheap,

Edited July 28, 2021 by placeholder

[gargamon]

Antibodies are only relevant while you are fighting a disease. When the disease is no longer present the antibodies naturally go away. Your body has mechanisms (such as T-cells) that remember previous infections and also remember how to generate new antibodies if you are exposed again. There is no way currently that I know of to measure the T-cells, etc.

 

So the bottom line is antibody counts are irrelevant.

[JupiterRising]

My view is this.

everybody in Thailand as expats have been blind to all that has been happening worldwide. You have not read outside news, neither have you worried about Covid due to the low cases. 
Now that covid is raging and will rage across the world (as you cannot stop a virus), all expats are panicking and asking so many questions that are easily answered and have been answered in the USA, Europe.

So, my advice to all expats that are now panicking, read up before you ask so many silly questions that are available in the mainstream media worldwide as TRUTH, and not conspiracy, or Thai pacification.

 

[internationalism]

5 hours ago, JupiterRising said:

My view is this.

everybody in Thailand as expats have been blind to all that has been happening worldwide. You have not read outside news, neither have you worried about Covid due to the low cases. 
Now that covid is raging and will rage across the world (as you cannot stop a virus), all expats are panicking and asking so many questions that are easily answered and have been answered in the USA, Europe.

So, my advice to all expats that are now panicking, read up before you ask so many silly questions that are available in the mainstream media worldwide as TRUTH, and not conspiracy, or Thai pacification.

 

this article is from reuters beijing office. Quotes research done in china. Also quotes philipino health minister. Gives examples from around the world. 

Thailand is only mentioned once and together with indonesia, as countries, which already mixing sinovac.

The thing is - sinovac is not used in the usa and europe, so there no experience with this vax there and no literature pubblished. It doesn't concern the more, than not approving this vax for an international travel.

There is a lot of info about all vaccines and all countries. The real problem is lack of readily available doses and badly designed vaccination programs. That is not only specific to thailand, but to many countries now, and in the recent past.

I don't sense any panic, far from generalising that all expats are acting irrationally and are misinformed.

Are you from some religious cult?