The CDC in America May 25th 2021 reports on this issue looks at breakthrough infections between January 1st and April 30th 2021.  

COVID-19 vaccines are a critical tool for controlling the ongoing global pandemic.  

The Food and Drug Administration issued emergency youth authorisations for three COVID-19 vaccines for use in the United States.  

In large, randomised control trials, each vaccine was found to be safe and efficacious in preventing symptomatic, laboratory confirmed COVID-19.  

Despite the high level of vaccine efficacy, a small percentage of fully vaccinated persons i.e. those who had received all the recommended doses of the FDA authorised COVID-19 vaccines developed symptomatic or asymptomatic infection with SARS-CoV-2.  

The CDC is working with state and territorial health departments to investigate SARS-CoV-2 infections amongst persons who are fully vaccinated and to monitor trends in case characteristics and SARS-CoV-2 variants are identified from persons with these infections.  

For this surveillance, a vaccine breakthrough infection is defined as the detection of SARS-CoV-2 RNA or antigen in a respiratory specimen collected from a person greater than or equal to 14 days after receipt of all recommended doses of an FDA authorised COVID-19 vaccine.  

State health departments voluntarily reported vaccine breakthrough infection to the CDC.  

When possible, genomic sequencing was performed on respiratory specimens that tested positive for SARS-CoV-2 RNA.  

A total of 10262 SARS-CoV-2 vaccine breakthrough infections had been reported from 46 US States and territories as of April 30th 2021.  Amongst these cases the low has been reported:

  • 6446, 63% occurred in females and the median patient age was 58 years  
  • Based on preliminary data 2725, 27% vaccine breakthrough infections were asymptomatic  
  • 995, that is 10% of patients, were known to be hospitalised 
  • 162, 2% of patients died  
  • Amongst the 995 hospitalised patients 289, 29% were asymptomatic or hospitalised for a reason unrelated to COVID-19  
  • The median age of patients who died was 82 years old  
  • 28, 18% were asymptomatic or died from a cause unrelated to COVID-19
  • Sequence data was available for 555 that is 5% of reported cases
  • 356, 64% of which are identified as SARS-CoV-2 variants of concern.  

As of April 30th 2021 approximately 101 million persons in the United States have been fully vaccinated against COVID-19.  

However, during the surveillance period, SARS-CoV-2 transmission continues at high levels in many parts of the country, with approximately 355,000 COVID-19 cases reported nationally during the week from April 24th to 30th 2021.  

Even though the FDA authorised vaccines are highly effective, breakthrough cases are expected, especially if poor population immunity reaches sufficient levels to further increase transmission.  

However, vaccine breakthrough infections occurred in only a small fraction of all vaccinated and accounted for a small percentage of COVID-19 cases.  

The number of COVID-19 cases, hospitalisations, and deaths that will be prevented amongst vaccinated persons far exceeds the number of vaccine breakthrough cases.  

To date, the age and sex distribution of reported vaccine breakthrough infections reflects a poorly vaccinated US population.  

The proportion of reported vaccine breakthrough infections attributed to variants of concern has also been similar to the proportion of these variants circulating throughout the United States.  

During March 28th to April 10th 2021 the aforementioned variants of concern accounted for 70% of the weighted estimates of SARS-CoV-2 lineages submitted to the CDC National genomic surveillance.  

These findings suggest that the re-infections are much more likely to be mild or asymptomatic.  

Out of 100 million US adults who have been fully vaccinated in the first four months the CDC only documented 10,000 breakthrough infections by the end of April and only 1000 of those resulted in hospitalisation; that is, only 1 in 100,000 vaccinated individuals were hospitalised with COVID during that period. 

LGP, the leading London doctors’ clinic commends the Government on its vaccination programme and encourages all those eligible to be vaccinated as soon as possible.

Dr Paul Ettlinger

Translate »
Share This