Transmission of SARS-CoV-2 Delta Variant Among Vaccinated Healthcare Workers, Vietnam

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.

Many interesting points in this article (16 pages of text) showing what an isolated outbreak of Delta is really like in terms of seriousness and infectiousness.

Also, they convert Cycle threshold values (Ct) to viral load values showing that high Ct values are in fact associated with low viral loads and possibly, when high enough, no virus at all.

The vaccines seem to have some effect against Delta but it’s not much as all those infected were fully vaccinated (except 1) and 75% (47 cases) developed symptoms.  Nobody died and only one needed oxygen.  The median age of the cases was 41.  Most symptomatic cases were mild.

They say some absurd things like it’s important to use masks to slow down this very transmissible thing and also that booster shots ought to be of some help.

It looks to me like vaccination is a pointless exercise to stop covid now that we have the Delta variant and we don’t really need it anyhow since it’s milder in its effects.  There was no mention of anyone being treated with Ivermectin or Hydroxycholorquine and yet everyone recovered just fine.  I imagine these treatments might have made the outbreak much shorted and even more milder and these drugs are certainly easily available in Vietnam I would assume since they treat diseases that are common there (malaria, parasites…).

Unfortunately there is no comparison with unvaccinated people because all the hospital staff were fully vaccinated.  So it’s hard to say what effect the vaccine has had in the increased viral loads, more than 215 times higher, than the strains circulating a year ago.  Delta causes high viral loads which are associated with higher symptoms but seems to be overall milder than older strains.

Also, the asymptomatic cases produce antibody responses almost as high as the symptomatic cases showing that asymptomatic infection (ie. you don’t feel sick) gives immunity as good as the more advanced, symptomatic kind.

There’s more.