A new study out of India indicates the great majority of so-called breakthrough infections are associated with the Delta variant of SARS-CoV-2. Sponsored by the India Council of Medical Research (ICMR), the apex research body of India for biomedical research, this study results indicate that the Delta variant was associated with a majority of infections associated with vaccinated individuals in nearly all of the 17 states and Union Territories covered by the study. Only 9.8% of these breakthrough infection cases required hospitalization, and deaths were associated with only 0.4% of the reported incidences. The takeaway from this study is that vaccination, even with one dose, offers greater protection against severe disease progression than those that are not vaccinated. Importantly, the authors imply that sufficient investment in continuous monitoring of post-vaccination breakthrough infections along with clinical severity needs to be incorporated into vaccination programs worldwide.
This yet-to-be-peer-reviewed study was recently uploaded to the preprint server medRxiv. This study centers on evaluating breakthrough infections, that is individuals who have been vaccinated yet still get infected by SARS-CoV-2, the virus behind COVID-19. Sponsored by the ICMR Pune Institute of Virology, the vaccinated individuals in the study received one or two doses of either A) Covishield, AstraZeneca/Oxford vaccine produced by Serum Institute of India or B) Covaxin, produced by the India biotech company called Bharat Biotech. The study collected 677 samples from individuals infected with breakthrough infections across 17 Indian states and Union Territories. Over 20% of the cases in the study were associated with co-morbidities, such as diabetes, chronic lung problems, and the like.
ICMR’s Department of Health Research capitalized on what is known in India as a network of Viral Research and Diagnostic Laboratories (VRDLs) as a means to track the breakthrough infections. The sponsors defined breakthrough infections as “the detection of SARS-CoV-2 RNA or antigen in a respiratory specimen collected from a person ≥14 days after receipt of all recommended doses of a COVID-19 vaccine.” Leveraging these VRDLs, the study team capitalized on “clinical and demographic” meta-data as well as “nasopharyngeal/oropharyngeal swabs (NPS/OPS)” in associated COVID-19 patients identified as positive (e.g. breakthrough infection) via “real-time RT-PCR” across 17 states and Union Territories (UTs) from April to May 2021. The study team reported that actual clinical specimens were “sequenced using next-generation sequencing (NGS)” in the effort to assess nucleotide variations in the SARS-CoV-2 genome associated with the specific variant strains.
Sponsored by ICMR Pune Institute of Virology, the study was led by Dr. Priya Abraham along with senior scientist Dr. Pragya Yadav and the results were reported widely in India across media, including The Times of India. Again, the study team conducted a genomic analysis of 677 COVID-19 cases who became infected even after receiving one dose of the vaccine (note that in India, at least four vaccines are in use).
As reported in multiple India press, a number of key takeaways include:
- 86.09% of the breakthrough infections were caused by B.1.617.2—the Delta variant of SARS-CoV-2
- ICMR reports that individuals with at least one infection are getting infected by this particular mutant strain
- The death rate among vaccinated individuals is very low—lower than those unvaccinated, indicating vaccines most certainly reduce hospitalization rates and death
- More specifically, of those vaccinated individuals infected with the Delta variant, only 9.8% required hospitalization while the mortality rate was 0.4%
- Delta is the primary driver for breakthrough infections
- The Delta variant dominates most regions of India except for the northern region where the Alpha variant is most common
Importantly, the study turned up a couple of new variants known as Delta AY.1 and AY.2. Both of them are associated with the K417N mutation “known to disrupt receptor-binding domain (RBD) binding capacity” thus establishing these variants as more transmissible in vaccinated individuals. According to the study authors, this indicates that SARS-Cov-2 is evolving to “evade immune responses and survive against the vaccines.”
The Delta variant of SARS-CoV-2 is associated with the majority of breakthrough infections (86.09%). The good news, however, is that vaccination is conferring considerable protection based on the subject sample of the study. Of the entire sample, only 9.8% of cases required hospitalization while mortality was only observed in 0.4% of the cases.
This study was funded via intramural financing associated with the ‘Molecular epidemiological analysis of SARS-CoV-2 circulating in different regions of India’ thanks to the ICMR, New Delhi—funds were transferred to ICMR National Institute of Virology, Pune.
Dr. Priya Abraham, ICMR Pune Institute of Virology
Note importantly what isn’t discussed are the hospitalization and mortality rates overall. For example, even prior to vaccines, a majority of cases—about 90% of COVID-19 cases—are recorded as either asymptomatic or mild-to-moderate. That means that the 9.8% hospitalization rate may not be too material a number. The overall mortality rates of COVID-19 vary from country to country. For example, in America, with approximately 34 million COVID-19 cases and 620 thousand deaths, the approximate mortality rate is around 2%. In India, with approximately 31 million recorded cases, the current reported total morality figure now stands at 414 thousand, meaning that the approximate mortality rate there is less than America at about 1.3%. These numbers are based on World Meters. These types of analyses need to be further investigated for a more granular understanding of protection on a country-by-country basis.
Call to Action: The study indicates that those individuals vaccinated, even with one dose, have more protection against COVID-19 than those that do not, based on the findings from this specific set of samples. Thus the study authors declare that continuous monitoring of post-vaccination breakthrough infections in association with clinical severity of disease must be incorporated into vaccination programs around the world. This will help public health authorities and research agencies better understand how to modify existing vaccines while informing the development of novel, superior vaccines of the future.