China Dishes Out First Aerosol COVID-19 Boosters Amid New Wuhan Lockdown
Shelves stand empty in a Wuhan supermarket in an earlier lockdown.

China administered the world’s first oral aerosol COVID-19 vaccine boosters in Shanghai on Wednesday, as new lockdown measures were imposed on Wuhan, the supposed birthplace of the pandemic.

Chinese vaccine manufacturer CanSino Biologics said in a media statement that the inclusion of its vaccine in Shanghai’s booster vaccination program marked “the start of the rollout of the world’s first inhaled COVID-19 vaccine, Convidecia Air”.

The inhaler, approved as a booster for adults last month by the National Medical Products Administration of China, “provides a non-invasive option that uses a nebulizer to change liquid into an aerosol for inhalation through the mouth”, according to the company.

“Convidecia Air is needle-free and can effectively induce comprehensive immune protection in response to SARS-CoV-2 after just one breath,” it added. The aerosol vaccine is based on Sinovac (marketed as CoronaVac).

The Chinese-developed Sinovac uses a modified version of an adenovirus to deliver inactive parts of SARS CoV2 to a person’s immune system to prime it recognise and attack the virus when it becomes infected. This is followed by a second vaccine to boost the immune system a few weeks later.

Results from a clinical trial that compared the oral aerosol vaccine to an injectable version of Sinovac, published in The Lancet in August, found that the aerosol elicited 6.7 to 10.7 more neutralising antibodies than the injection after two to four weeks.

However, Sinovac is less efficacious against COVID-19 than mRNA vaccines, and there are some early indications that it offers very little protection against the latest variants.

Nasal sprays

Meanwhile, there are other clinical trials of SARS-CoV-2 vaccines delivered through the mucosa, but these are all nasal sprays.

Researchers at Yale University in the US recently published a pre-print paper reporting early success in mice using a vaccine booster strategy, “prime and spike”.

Noting that protection offered by mRNA vaccines weakens fairly fast, particularly in the nasal mucosa and respiratory tract, in those already vaccinated (“primed”), they tested an intranasal “spike” to “elicit mucosal immune memory within the respiratory tract”. 

Their trial found that “prime and spike” induced a robust immune response in animals that protected against SARS-CoV-2 infection. 

Indian company Bharat has also developed an intranasal vaccine for Covaxin, which it says has been successful in animal studies although it has not yet submitted results for peer review.

Wuhan locks down

Meanwhile, China has locked down Wuhan’s central Hanyang district after COVID cases were found, as China persists with a zero-tolerance approach almost three years after the virus was first reported in the city, and about 900,000 residents were told to stay at home, according to Bloomberg.

This follows the re-election of Chinese President Xi Jinping – the architect of the “zero-COVID” strategy – for a third five-year term as leader of the country’s ruling communist party.

China’s zero-COVID strategy has resulted in lockdowns of entire cities. People living in districts where COVID-19 cases are detected are obliged to stay indoors for seven days and take a daily test.

The lockdowns have had a negative effect on the country’s economy, with a 1.7% contraction in sales last month largely as a result of quarantines in various parts of the country.

Meanwhile, a 14-year-old girl teenager, Guo Jingjing, died in a quarantine facility earlier this month, according to the BBC.

She apparently developed a fever two days after being taken to a facility in Ruzhou, and her family posted videos on social media of her shaking and convulsing on a bed. Her father, Guo Lele, said in a video on Douyin (Chinese TikTok) that the facility had not provided her with any help.

However, the videos and most references to the incident have since been removed.

Image Credits: Studio Incendo.

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