Comparison of mRNA-1273 and BNT162b2 Vaccines on Breakthrough SARS-CoV-2 Infections, Hospitalizations, and Death During the Delta-Predominant Period

”…The 60-day hospitalization risk was 12.7% (392/3078) for mRNA-1273 [MODEERNA]recipients and 13.3% (2489/18 737) for BNT162b2 [PFIZEER] recipients. The 60-day mortality was 1.14% (35/3078) and 1.10% (207/18 737) for mRNA-1273 and BNT162b2 recipients, respectively. Among the matched cohorts, mRNA-1273 recipients (n = 3054) had a lower risk of 60-day hospitalizations than BNT162b2 recipients (n = 3054) (HR, 0.80; 95% CI, 0.70-0.91). No significant difference was observed for mortality (HR, 0.79; 95% CI, 0.50-1.23).

J. Harris: As far as I can see, with the Delta Variant, there not much difference in which one of the mRNA vaccines one takes. I’m still looking for a good “Mix and Match” vaccine article.

COVID-19 Cases and Hospitalizations by COVID-19 Vaccination Status and Previous COVID-19 Diagnosis — California and New York, May–November 2021

”…What is added by this report?

During May–November 2021, case and hospitalization rates were highest among persons who were unvaccinated without a previous diagnosis. Before Delta became the predominant variant in June, case rates were higher among persons who survived a previous infection than persons who were vaccinated alone. By early October, persons who survived a previous infection had lower case rates than persons who were vaccinated alone.’


COVID-19 IMMUNE LANDSCAPE With cases of COVID-19 continuing to surge worldwide due to the Omicron variant of concern (VOC), scientists are looking to recent experiences with the Delta variant to shed insight into what the immune landscape might look like for individuals who are unvaccinated and have recovered from previous SARS-CoV-2 infection, those who are vaccinated, and those who are both recovered and vaccinated. The world will be in a significantly different place after Omicron subsides, with millions of people having at least short-term immune memory of its distinct S-gene mutations. More people than ever before will have some form of natural immunity against SARS-CoV-2, but it is unclear the extent to which recent infection might protect against future infection or hospitalization. In a new report[ABOVE] published in the US CDC’s Morbidity and Mortality Weekly Report (MMWR), researchers examined case and hospitalization rates in New York and California during the surge of the Delta VOC. They describe a complex immune landscape through the beginning of Delta’s takeover to the time when it became the predominant global variant. 

Initially, in May 2021, vaccinated persons with no prior infection had the lowest rates of hospitalization, but as Delta began to infect more people and cause breakthrough cases, individuals with previous infection were less likely to be hospitalized compared to unvaccinated persons with no prior infection. From May 2021 to June 2021, vaccinated persons with no prior infection had the lowest hospitalization rates of any other group at 27.7-fold lower compared with unvaccinated persons with no prior infection. But from October 2021 to November 2021, hospitalization rates among vaccinated persons with prior infection were 57.5-fold lower and 55.3-fold lower among unvaccinated individuals with prior infection, compared with unvaccinated individuals with no prior infection. By comparison, hospitalization rates in vaccinated persons with no prior infection were 19.8-fold lower. These data suggest that natural immunity from prior infection can play an important role in preventing severe consequences of subsequent SARS-CoV-2 infections, even among those who have not been fully vaccinated. 

Some important context to these findings is that the shift in protection from vaccine-alone to vaccine-plus-prior infection occurred during a time of known waning immunity from initial rounds of vaccination. Additionally, people who were fully vaccinated with an additional booster dose were not evaluated as a separate group in this study. All of these data point to having high levels of antibodies—whether vaccine-induced, naturally acquired, or a combination—as vital in protecting against hospitalization and severe COVID-19 outcomes. It is still unclear whether these patterns will hold for the Omicron VOC, which has a greatly different viral profile compared with previous variants. Hospitals are still reporting that the unvaccinated have the highest risk of severe COVID-19, while the group with the lowest risk of severe COVID-19 are those who are fully vaccinated and boosted, underscoring the continuing need for vaccines and booster doses.  

A word of caution: Some might interpret these findings as a “green light” to ignore all COVID-19 precautions and take unnecessary risks for themselves and others. Even if natural immunity does confer protection for an extended time, the consequences of contracting and recovering from COVID-19 cannot be overstated; it is estimated that 15-80% of people recovering from illness will experience “long COVID,” or prolonged symptoms including brain fog, dizziness, loss of taste and smell, and other symptoms which can alter daily life for those affected. While those who might get COVID-19 twice do seem fortunate in that their bodies are better able to fight off the newest infection, it is still better never to become infected with SARS-CoV-2 because of the uncertainties of long-term sequelae. Vaccines, masks, and physical distancing are all still vital tools in bringing an end to the pandemic with as few deaths as possible.

      Coming tomorrow, a Chicken Pox story



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