EID Journal: Breakthrough Infections of SARS-CoV-2 Gamma Variant in Fully Vaccinated Gold Miners, French Guiana, 2021

Credit ACIP/CDC    

#16,076

In a perfect world, all vaccines would be 100% effective in preventing infection, and that would be that.  But the world we live in is far from perfect. Individuals - due to age, genetics, health problems, environmental factors, or the medications they take - have vastly different immune systems.

Add in  the ability of new virus strains or variants to emerge and `vaccine effectiveness' (VE) can cover a lot of territory; prevention of infection, prevention of symptomatic illness even if infected, or greatly reduced risk of hospitalization or death from infection. 

While I'm thankful to be fully vaccinated against COVID, the reality is, being double-jabbed isn't a guarantee against future SARS-CoV-2 infection. Being vaccinated reduces the chances of being infected - probably substantially - but doesn't eliminate the risk entirely. 

More importantly, being vaccinated against COVID greatly reduces your odds of developing severe disease, hospitalization, or death.  Again, no guarantee, but like wearing seatbelt in your car - your odds of walking away unscathed are substantially improved. 

These are reasons why, as I've explained in the past, that I've elected to continue to wear a face mask in public and avoid crowded indoor spaces, even though I'm fully vaccinated, and intend to do so for the foreseeable future. 

Admittedly, this more nuanced messaging is difficult to convey to a skeptical population, who are constantly being bombarded by anti-vaccination messaging on social media.  But as we invariably see more and more fully vaccinated individuals fall ill with COVID, it is important to put it into context.  

Vaccine `breakthrough' - even if a vaccine is 90% effective in preventing infection - will affect millions of people.  And even if a vaccine is 99% effective in preventing deaths from COVID, tens of thousands of vaccinated people could still die from the disease. 

All of which brings us to a new EID Dispatch that reports on a 60% COVID breakthrough rate among fully vaccinated miners in French Guiana when challenged by the Gamma (aka P.1.) Variant.  While some percentage of breakthrough cases are to be expected, these are exceptionally high numbers. 

First, some excerpts from the Dispatch (follow the link to read it in its entirety), then I'll return with a postscript. 

Volume 27, Number 10—October 2021
Dispatch
Breakthrough Infections of SARS-CoV-2 Gamma Variant in Fully Vaccinated Gold Miners, French Guiana, 2021

Nicolas Vignier1 , Vincent Bérot1, Nathalie Bonnave, Sandrine Peugny, Mathilde Ballet, Estelle Jacoud, Céline Michaud, Mélanie Gaillet, Félix Djossou, Denis Blanchet, Anne Lavergne, Magalie Demar, Mathieu Nacher, Dominique Rousset, and Loïc Epelboin

Abstract 

An outbreak of severe acute respiratory syndrome coronavirus 2 caused by the Gamma variant of concern infected 24/44 (55%) employees of a gold mine in French Guiana (87% symptomatic, no severe forms). The attack rate was 60% (15/25) among fully vaccinated miners and 75% (3/4) among unvaccinated miners without a history of infection.

On May 31, 2021, a gold miner tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at the Cacao health center, French Guiana. He worked in a legal gold mine located 72 km from Cayenne (including 13 km of forest trail) in the Amazon Forest. Other workers from the same site were reported as symptomatic, although a large part of this specific population had benefited from complete coronavirus disease (COVID-19) vaccination in the previous month. A medical team went on site to investigate, examine, and screen the 44 employees of the mine. We describe results of the outbreak investigation.

          (SNIP)

Conclusions

We describe a COVID-19 Gamma variant cluster with a high attack rate even in fully vaccinated persons. The Gamma variant is the predominant variant in French Guiana which, as of July 2021, caused a third epidemic wave, threatening to overwhelm the hospital capacity (11). Such a low vaccine efficiency against infection by the Gamma variant was not expected because in vitro studies have shown a similar reduction of neutralization for Beta or Gamma variants by BNT162b2-elicited antibodies (5) and a conserved CD4+ T-cell response against spike proteins from the Beta variant (6).

Of the 10,262 COVID-19 vaccine breakthrough infections identified in the United States during January–April 2021, for which 555 had available sequencing, only 28 were caused by the Gamma variant (12). Furthermore, real-world effectiveness against any infection by a Beta variant, which shares a similar E484K mutation on the gene coding for the spike protein, was estimated at 75.0% (9). Given the surprisingly high attack rate, we hypothesized potential dysfunctions of conservation or administration of vaccines, but the absence of traceable cold-chain interruption and the use of different batches seemed to refute this hypothesis. The relative isolation of the mining site and careful contact tracing suggested limited numbers of viral introductions inside this community.

The low Ct of positive PCR for SARS-CoV-2 despite prior vaccination suggested that a complete vaccination scheme with BNT162b2 vaccine was not sufficient to prevent symptomatic SARS-CoV-2 infection and its transmission in this context of communal life without masks. The working conditions of some miners (heat, humidity, aerosol) and the sharing of machine cabs for others could also have contributed to transmission. The absence of severe COVID-19 in a high-risk population (13) suggests but does not prove protection against severe disease, as reported for the Beta variant in another context (14).

In conclusion, we describe a VOC Gamma COVID-19 outbreak with a strikingly high attack rate among persons fully vaccinated with BNT162b2 vaccine. Our observation suggested that BNT162b2 protected from severe COVID-19. However, this single unexpected outbreak in a small and isolated vaccinated population requires further real-life studies on BNT162b2 vaccine effectiveness against the VOC Gamma. Masking and social distancing —even among those fully vaccinated— may be necessary among persons with frequent exposure in Gamma variant–endemic zones.

 

Dr. Vignier is a public health and infectious disease physician in the Department of Research, Innovation and Public Health (Centre Investigation Clinique Antilles Guyane) and Infectious Disease Department of the Cayenne Hospital in French Guiana. His primary research interests include tropical medicine, migrant health, and social epidemiology. Dr. Bérot is a dermatology and infectious disease physician in the Infectious Disease Department of the Ouest Guyanais Hospital in French Guiana. His primary research interests include tropical disease and skin infections.

 

The Gamma variant, which has ravaged Brazil since December, has already displayed the ability to overcome acquired immunity from prior COVID infection (see  The Lancet: Resurgence of COVID-19 in Manaus, Brazil, Despite High Seroprevalence), and is currently considered a VOC (Variant of Concern) by the CDC.

P.1 (Pango lineage)a

Spike Protein Substitutions: L18F, T20N, P26S, D138Y, R190S, K417T, E484K, N501Y, D614G, H655Y, T1027I

Name (Nextstrain)b: 20J/501Y.V3

WHO Label: Gamma

First Identified: Japan/Brazil

BEI Reference Isolatec: NR-54982

Attributes:

• Significantly reduced susceptibility to the combination of bamlanivimab and etesevimab monoclonal antibody treatment,7 but other EUA monoclonal antibody treatments are available 14
• Reduced neutralization by convalescent and post-vaccination sera15

While Gamma is currently being outpaced by the Delta Variant - both in the United States, and around the world - is is holding on remarkably well in some regions (including the state of Illinois), and that could position it to take over once Delta has run out of susceptible hosts. 

Assuming, of course, something even more `biologically fit' doesn't come along to usurp Gamma as the heir apparent. 

The take-away from this report isn't that our vaccines are worthless. Far from it.  Only that vaccines alone probably aren't going to be enough to stop the community transmission of some of the more aggressive variants.

And while admittedly disappointing, we continue to see evidence suggesting the vaccine still greatly reduces the odds of severe illness, hospitalization, or death. 

As tired as we all are of dealing with COVID, this virus shows no signs of being tired of dealing with us.   

Which is why, tired or not, we must continue to adapt our strategies and adjust our expectations if we are to successfully deal with this evolving pandemic threat.