Does a study say fully vaccinated health care workers carry 251 times the viral load of unvaccinated and pose a threat to unvaccinated patients and co-workers? No, that's not true: This is a distortion of what the published paper actually says. The paper studied vaccinated health care workers who were infected with COVID-19 in June 2021 versus health care workers in March and April 2020. The paper found health care workers infected by the delta variant carried viral loads 251 times higher than those infected with earlier strains of the SARS-CoV-2 virus.
The claim appeared as an article published by Children's Health Defense on August 23, 2021, titled "Study: Fully Vaccinated Healthcare Workers Carry 251 Times Viral Load, Pose Threat to Unvaccinated Patients, Co-Workers" (archived here), which opened:
A preprint paper by the prestigious Oxford University Clinical Research Group, published Aug. 10 in The Lancet, found vaccinated individuals carry 251 times the load of COVID-19 viruses in their nostrils compared to the unvaccinated.
Users on social media only saw this title, description and thumbnail:
Study: Fully Vaccinated Healthcare Workers Carry 251 Times Viral Load, Pose Threat to Unvaccinated Patients, Co-Workers
A preprint paper by the prestigious Oxford University Clinical Research Group, published Aug. 10 in The Lancet, found vaccinated individuals carry 251 times the load of COVID-19 viruses in their nostrils compared to the unvaccinated.
Children's Health Defense is headed by Robert F. Kennedy Jr., a well known anti-vaccine advocate and conspiracy theorist. Lead Stories has debunked other false claims that he has made, which are collected here.
The article claims:
A preprint paper by the prestigious Oxford University Clinical Research Group, published Aug. 10 in The Lancet, found vaccinated individuals carry 251 times the load of COVID-19 viruses in their nostrils compared to the unvaccinated.
This is misleading and taken out of context. The paper published on SSRN.com on August 10, 2021, is titled, "Transmission of SARS-CoV-2 Delta Variant Among Vaccinated Healthcare Workers, Vietnam. "Preprint" means other doctors and scientists have not yet reviewed the findings. SSRN.com is a site that offers public access to papers science journals like The Lancet have identified as being of interest.
The vaccinated individuals were tested and studied in June 2021, which was seven to eight weeks after they received their second dose of the vaccine. It was determined that they were infected with the delta variant. Their viral loads were compared to people who were infected with COVID-19 between March and April 2020. The vaccinated health care workers with COVID-19 were not compared to people who did not have COVID-19 or who were unvaccinated in 2021. The paper concluded the virus load is 251 times higher in people who were infected with the delta variant in 2021 compared to people who were infected with COVID-19 in 2020. There was not a vaccine available in 2020 and the delta variant had not yet come into existence.
The paper noted, "Viral loads of breakthrough Delta variant infection cases were 251 times higher than those of cases infected with old strains detected between March-April 2020":
Findings: Between 11th-25th June 2021 (week 7-8 after dose 2), 69 healthcare workers were tested positive for SARS-CoV-2. 62 participated in the clinical study. 49 were (pre)symptomatic with one requiring oxygen supplementation. All recovered uneventfully. 23 complete-genome sequences were obtained. They all belonged to the Delta variant, and were phylogenetically distinct from the contemporary Delta variant sequences obtained from community transmission cases, suggestive of ongoing transmission between the workers. Viral loads of breakthrough Delta variant infection cases were 251 times higher than those of cases infected with old strains detected between March-April 2020. Time from diagnosis to PCR negative was 8-33 days (median: 21). Neutralizing antibody levels after vaccination and at diagnosis of the cases were lower than those in the matched uninfected controls. There was no correlation between vaccine-induced neutralizing antibody levels and viral loads or the development of symptoms.
The Children's Health Defense article claimed:
The conclusions of the Chau paper support the warnings by leading medical experts that the partial, non-sterilizing immunity from the three notoriously "leaky" COVID-19 vaccines allow carriage of 251 times the viral load of SARS-CoV-2 as compared to samples from the pre-vaccination era in 2020.
And continued:
Vaccinated individuals are blasting out concentrated viral explosions into their communities and fueling new COVID surges. Vaccinated healthcare workers are almost certainly infecting their coworkers and patients, causing horrendous collateral damage.
This is not what the conclusion of the paper was. It simply said those infected in 2021 with the delta variant have a higher viral load than those infected with COVID-19 in 2020, not that the vaccine "allowed" the higher viral load. The delta variant makes the viral load higher, not the vaccine people have received:
Implications of all the available evidence
Our study provided strong evidence demonstrating for the first time the transmission between vaccine breakthrough cases infected with the Delta variant. High viral loads coupled with prolonged PCR positivity and poorly ventilated indoor setting without in-office mask wearing might have facilitated the transmission between vaccinated healthcare workers. The absence of correlation between neutralizing antibody levels and peak viral loads suggested that vaccine might not lower the infectivity of breakthrough cases. Given the rapid spread of the Delta variant worldwide, physical distancing measures remain critical to reduce the transmission of SARS-CoV-2 Delta variant, event in countries where vaccination coverage is high.
