What are the Sinopharm vaccine side effects and is a Pfizer booster shot safe?

New studies show the shot is effective against the Delta variant and a dose of Pfizer-BioNTech can be taken safely as a booster

This is an updated version of an article that was first published in June 2021

Follow the latest updates on the Covid-19 pandemic here

Sinopharm’s Covid-19 vaccine is effective against the Delta variant and can be safely followed with a Pfizer-BioNTech booster shot, researchers have found.

In July, a small study carried out in Sri Lanka found it to be effective against the highly contagious Delta coronavirus variant.

Moreover, medics in the UAE said the immune system response was very strong once a double dose of the Sinopharm vaccine was topped up with a booster shot of the Pfizer-BioNTech vaccine.

On August 2, the country’s health ministry approved the Sinopharm vaccine for use on children aged between 3 and 17. The decision followed a trial involving 900 children in Abu Dhabi.

What are the latest developments on the vaccine? How effective is it? How long does the protection last?

And how does it compare with other vaccines?

The National explains.

Is the Sinopharm vaccine effective against Covid-19?

Tests in the UAE suggested the vaccine was 86 per cent effective against preventing infection in Phase-3 trials involving 31,000 people. The manufacturer revised the figure to 79.34 per cent after it received more data.

Doctors say the most important consideration is whether it prevents people becoming seriously ill.

Dr Nawal Al Kaabi, chairwoman of the National Covid-19 Clinical Management Committee, said there were no critical care admissions or deaths among those who had been immunised in Abu Dhabi, making it 100 per cent effective against serious disease. People who were infected after taking both doses of the vaccine mostly remained asymptomatic or presented only mild symptoms, she said.

In May, a report published in the Journal of the American Medical Association found the vaccine prevented symptomatic infections by 72.8 per cent and 78.1 per cent, largely in line with what the state-owned drugmaker previously announced.

Although the Pfizer-BioNTech vaccine has proven to be extremely effective, it has not been shown to prevent serious disease entirely.

In Israel, the Pfizer-BioNTech shot, if both doses were administered, was found to be 87 per cent effective at preventing conditions requiring hospital treatment and 92 per cent effective at preventing severe disease.

It was 72 per cent effective at preventing death 14 to 20 days after the first dose, officials said.

How effective is Sinopharm against new strains?

A recent small study carried out in Sri Lanka showed the Sinopharm vaccine is effective against the highly contagious coronavirus Delta variant.

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 with Sars-CoV-2.

“Antibody responses to Delta variant and neutralising antibodies were similar to levels seen following natural infection,” they said.

But antibody responses were lower in the over-60s than in people aged 20 to 39, the researchers said.

“Seroconversion rates and immunogenicity appear to be lower in older individuals,” they wrote in a paper that has 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.

A February study suggested the Sinopharm vaccine is less effective against the South African variant also known as Beta, but it still works.

Researchers tested a blood sample from a patient who received the vaccine against that strain.

It is one of the most worrying variants because it is more contagious and includes a mutation that helps it evade the neutralising antibody responses of people who were infected with the original virus.

It shares this mutation with the Gamma variant, from Brazil.

The Sinopharm vaccine resulted in a 1.6-fold reduction in antibodies against the variant, largely preserving its neutralisation.

This means the variant does not escape the immunity induced by the vaccine, the researchers said.

Boxes of China's Sinopharm COVID-19 vaccine are seen during vaccination at the Guru Nanak Darbar Gurudwara (Sikh temple) in Dubai on February 28, 2021.  / AFP / Karim SAHIB

Can Sinopharm be adapted to fight the new variants?

Yes. Speaking on Chinese television, Wang Hui, general manager of the Beijing Institute of Biological Products, a subsidiary of Sinopharm Group, said the company has “measures in place to handle the situation if the strength and efficacy of the vaccine drops”.

“We have plans to develop and produce co-strain and multi-strain vaccines,” she said.

On March 18, Professor Wang Junzhi, deputy head of an expert task force on vaccine development in China, described the Covid-19 mutations as an issue of “great importance” in a press conference with global media.

“We are taking proactive measures to develop a new generation of vaccines,” he said.

How long does the protection offered by the vaccine last?

Current estimates by the UAE government suggest two doses of the vaccine may offer immunity for four to six months.

The vaccine mainly induces antibodies against one protein of the virus: the spike. These are known as anti-S or anti-spike antibodies.

Anything above 15 arbitrary units per millilitre (au/ml) is positive for the anti-S antibody test.

A typical result after the Sinopharm vaccine is anything between 50au/ml and 150au/ml.

It also generates neutralising antibodies that roughly correlate to the anti-spike antibodies.

Dr Sally Mahmoud, lab director at Biogenix Labs, part of G42 Healthcare in Abu Dhabi, said some people it is monitoring still have antibodies after almost eight months. But in others, there is a drop in antibodies after a couple of months.

How does this compare with other Covid-19 vaccines?

Most vaccine manufacturers have yet to release any data to answer this question.

In December, Moderna released a study showing its vaccine still offered good responses four months after the first vaccination.

Levels of spike antibodies and neutralising antibodies “declined slightly over time, as expected, but they remained elevated in all participants three months after the booster vaccination”, researchers in The New England Journal of Medicine said.

The latest research funded by the US drugmaker and German research lab, found the Pfizer-BioNTech coronavirus vaccine has a gradual but steady decline in effectiveness within months of the second dose being taken.

A vaccinated person’s protection against the virus drops to about 84 per cent after four months, still making it highly effective.

The study has not yet been peer-reviewed but was released as Pfizer bids for approval from US regulators for a third, or booster, dose for vaccinated people, where needed. US authorities have said no booster is required yet.

Can UAE residents get a third ‘booster’ shot of Sinopharm or Pfizer-BioNTech?

Dubai residents are eligible to take a booster shot of Pfizer-BioNTech three months after their last Sinopharm dose.

In Abu Dhabi, residents must wait six months after their last Sinopharm dose. They can choose between Pfizer-BioNTech or Sinopharm. Authorities have advised residents to take one Pfizer shot only as a booster. But in some cases they have been able to obtain two doses after receiving a doctor’s consent.

People working in the healthcare sector in Abu Dhabi can receive the booster shot three months after their second Sinopharm dose.

Sinopharm vaccine side effects

There are no published studies yet that have focused on Sinopharm vaccine side effects. But as with other “inactivated” vaccines, the side effects appear to be mild.

Anecdotally, people report a sore arm and minor swelling, with others feeling fatigue or symptoms similar to a cold, which pass in a few days.

In contrast, messenger RNA vaccines, such as Pfizer-BioNTech and Moderna, appear to come with more side effects.

According to a US Centres for Disease Control report, as of December 19, 112,807 people had received the vaccine.

Of these, 3,150 – or 2.8 per cent – had suffered “health impact events”, listed as the inability to perform everyday activities, taking time off work or seeing a doctor as a precaution.

How long does protection from Covid-19 antibodies last?

Concerns have been raised that antibodies to the virus fade quickly.

A large study carried out by Imperial College London in the autumn, involving 365,000 people, showed antibody levels dropped by a quarter in three months.

The findings built on previous research, which also found evidence of waning antibody counts.

One recent study from researchers at the University of Montreal showed antibody levels in the blood drop rapidly after infection.

But antibodies are only one piece of the complex puzzle when it comes to immunity.

Another study, led by the UK coronavirus immunology consortium of 100 healthcare workers six months after infection, found that while antibody levels had dropped for some people, their T-cell response, a type of white blood cell that attacks cells infected with the virus, remained robust.

The finding was replicated by other research performed in the US, which showed recovered Covid-19 patients still had enough immune cells to fight the virus eight months on.

Sinopharm vaccine for children

The UAE’s Ministry of Health and Prevention has approved the Sinopharm Covid-19 vaccine for children aged between 3 and 17.

The approval follows a trial involving 900 children in Abu Dhabi.

“The decision comes after clinical trials and extensive evaluations and is based on the emergency-use authorisation and local evaluations,” the ministry said.

Department of Health Abu Dhabi said the study tracked the vaccine’s effectiveness in reducing the infection rate and severity of symptoms among target groups.

The results will be released later.

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