A two-dose COVID-19 vaccine from China's Sinopharm was 50.4% effective in preventing infections in health workers in Peru during a COVID-19 surge in cases fuelled by virus variants, and booster shots can be considered, a study found.
Reuters reports that the study, involving Sinopharm's BBIBP-CorV vaccine, which looked at data from February until June when Peru was fighting a brutal second-wave of infections fuelled by the Lambda and Gamma variants of the coronavirus, was conducted on nearly 400,000 frontline health workers. Most received two doses of the vaccine.
"The efficacy to prevent infection is not high, which is something to consider once a high percentage of the population receives its two doses, (the) moment when boosters can be considered to optimise the protection of frontline health workers," said the study published last week from scientists at Peru's National Institute of Health and two other research institutes.
The vaccine, however, was 94% effective at preventing deaths after two doses, it added.
Some countries, including Cambodia and the United Arab Emirates, have offered vaccines made by AstraZeneca or Pfizer as boosters to those who received doses of China's Sinopharm.
"The most likely thing is you will indeed need a third dose at some point: the question is when, and with what type of vaccine," Lely Solari, one of the seven authors of the paper, told Reuters.
Solari said that while the efficacy of Sinopharm's vaccine against infections was found to be low, it was still acceptable by the World Health Organization (WHO) standards. It had shown a 78.1% efficacy rate against symptomatic COVID-19 cases in Phase III clinical trials, WHO data showed. An announcement from Peru's ministry of health said last month the vaccine was 98% effective against deaths.
Peru has the highest pandemic death count per capita in the world, which scientists say was caused by the Lambda variant first identified late last year and made worse by a fragile healthcare system.
The Lambda variant recently grabbed headlines because of its spread in the United States and other Latin American nations, though several infectious disease experts said the spread of the variant may be receding. The variant is more resistant to antibodies triggered by vaccines than the original version of the virus that emerged from Wuhan, based on lab study results, Japanese researchers said in a paper ahead of peer review.
While the Peru study included asymptomatic infections, Solari cautioned that they didn't conduct real-time testing to identify infections rigorously.
"The vast majority of tests took place because health workers developed symptoms," Solari said. "Some got tested because they suspected infection, but the vast majority was because they had symptoms."
Peruvian health workers were vaccinated exclusively with the Sinopharm shot because that was the first to arrive in Peru and their group was the first to be vaccinated. The country has also vaccinated some people with vaccines from Pfizer and AstraZeneca.
SARS-CoV-2 Lambda variant exhibits higher infectivity and immune resistance
Izumi Kimura, Yusuke Kosugi, Jiaqi Wu, Daichi Yamasoba, Erika P Butlertanaka, Tanaka, Yafei Liu, Kotaro Shirakawa, Yasuhiro Kazuma, Ryosuke Nomura, Yoshihito Horisawa, Kenzo Tokunaga, Akifumi Takaori-Kondo, Hisashi Arase, The Genotype to Phenotype Japan (G2P-Japan) Consortium, Akatsuki Saito, So Nakagawa, Kei Sato
Published in bioRxiv 28 July 2021
SARS-CoV-2 Lambda, a new variant of interest, is now spreading in some South American countries; however, its virological features and evolutionary trait remain unknown. Here we reveal that the spike protein of the Lambda variant is more infectious and it is attributed to the T76I and L452Q mutations. The RSYLTPGD246-253N mutation, a unique 7-amino-acid deletion mutation in the N-terminal domain of the Lambda spike protein, is responsible for evasion from neutralising antibodies.
Since the Lambda variant has dominantly spread according to the increasing frequency of the isolates harbouring the RSYLTPGD246-253N mutation, our data suggest that the insertion of the RSYLTPGD246-253N mutation is closely associated with the massive infection spread of the Lambda variant in South America.
Lambda S is highly infectious and T76I and L452Q are responsible for this property; Lambda S is more susceptible to an infection-enhancing antibody; RSYLTPGD246-253N, L452Q and F490S confer resistance to antiviral immunity.
Epidemic dynamics of the Lambda variant in South American countries
As of 29 June 2021, 1,908 genome sequences of the Lambda variant belonging to the PANGO C.37 lineage have been isolated from 26 countries and deposited in GISAID. Although it is considered that the Lambda variant was first detected in Peru in December 2020 (WHO, 2021a), our in-depth analysis revealed that the Lambda variant was first detected in Argentina on 8 November 2020. The fact that the percentage of the Lambda sequence is increasing in South American countries including Peru, Chile, and Argentina suggests that the Lambda variant is spreading predominantly in these countries. We generated a maximum likelihood-based phylogenetic tree of the Lambda variant.
Although there are some isolates that have been misclassified as the Lambda, which could be a sister group of the Lambda variant, our phylogenetic tree indicated the monophyly of genuine Lambda variant isolates.
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