A staff member checks the packaging quality of COVID-19 inactivated vaccine products at a packaging plant of the Beijing Biological Products Institute Co., Ltd. in Beijing, capital of China, Dec. 25, 2020.Photo:Xinhua

Chinese experts reiterated the necessity of taking strict protective measures after former Peruvian president Martín Vizcarra announced that he and his wife tested positive for the COVID-19 despite being vaccinated in October last year. 

The Vizcarras announced their infections on Twitter on Sunday, saying that they showed symptoms and are under quarantine. He claimed that he had taken strict measures after receiving doses from Sinopharm. 

The efficacy of Sinopharm's inactivated vaccines against infections with symptoms is about 70 percent, and no vaccine is 100 percent effective. It is "not at all surprising" to see infection cases despite vaccinations, Tao Lina, a Shanghai-based vaccine expert, told the Global Times on Monday.

"That is why Chinese authorities and producers have always been calling for taking strict protective measures following vaccination," Tao said.

On the vaccination notice Chinese local authorities released, it clarified that "vaccination is not 100 percent effective, as herd immunity has not been built. Please continue to wear masks, wash hands frequently, open windows and keep social distance."

Two of Sinopharm's COVID-19 vaccines, which showed 79 percent and 73 percent efficacy respectively, had undergone Phase-III clinical trials and were used in mass vaccinations in Peru.  

Chinese experts also noted that the severity of the COVID-19 epidemic and possible mutations spreading in Peru would also affect the efficacy of existing vaccines.

Peru has been experiencing a second round of the epidemic since January, local health officials told media. The country, with a population of about 32 million, had reported more than 1.7 million cases with about 60,000 deaths as of Monday, according to the website of the Johns Hopkins University.

According to a recent study by the Universidad Peruana Cayetano Heredia in Peru, a new novel coronavirus variant C.37 is emerging rapidly in the country and has also expanded into Chile and reported in Argentina, Australia, Brazil, Ecuador, Germany, Spain, the UK, and the US.

It is still unclear how contagious this variant is, or if it is the reason for Peru's current outbreak.  

No further information related to Vizcarra's infection has been released so far, and Sinopharm has not replied to the Global Times as of press time.  

Some netizens expressed concerns under Vizcarra's Twitter post over the efficacy of the Sinopharm vaccine. But others, who claimed to be Peruvian medical workers, noted that there is no vaccine that can protect recipients 100 percent and people have to keep necessary protective measures against the virus. 

Some people also posted photos of Vizcarra in public activities sharing food with others and walking without wearing a mask, doubting he "took strict measures." 

Vizcarra has faced criticism for not wearing a mask or following physical distancing rules during his election campaign ahead of the April 11 polls to choose Peru's next Congress and president, media reported.