Breakthrough infection of the vaccine with a variant of SARS-CoV-2

To the editor

Article by Hacisuleyman et al. (Released online on April 21)¹ There is growing concern about SARS-CoV-2 variants and vaccine breakthroughs. The authors describe two fully vaccinated women over the age of 50. The woman subsequently underwent a breakthrough infection with the variant vaccine.

The authors do not report a measurement of T cell response specific for SARS-CoV-2. T cell immunity is important for the regulation of SARS-CoV-2² It can be important for potential cross-reactivity protection against variants. The SARS-CoV-2 messenger RNA (mRNA) vaccine produces a weaker T cell response than other vaccine platforms.³ Studies of several combination vaccines are ongoing or planned, but the effect of vector boosting of the mRNA vaccine prime on T cell responses is currently unknown.

Because the Covid-19 vaccine differs in terms of immunogenicity and immunospecificity, it is advisable to consider a vaccine boost with a T cell-distorted vaccine after mRNA vaccination. Cross-defense T cell immunity generation. Preventing vaccine failure due to variants is an important part of pandemic management.

Douglas F. Nixon, MD, Ph.D.
Lishomwa C. Ndhlovu, MD, Ph.D.
Weil Cornell Medicine, NY, NY
[email protected]

This letter was published on June 2, 2021 on NEJM.org.

To the editor

Hacisuleyman etc. A cohort of 417 healthcare workers who received both the BNT162b2 (Pfizer–BioNTech) or mRNA-1273 (Moderna) vaccines reported a 0.5% incidence of breakthrough infections. Here we present data on breakthrough infections in a cohort of healthcare workers at a tertiary care hospital in India who received the ChAdOx1 nCoV-19 (recombinant) vaccine. Of the 12,248 healthcare workers, 7,170 (58.5%) received the first vaccination and then 3,650 (29.8%) received the second vaccination, according to the guidelines of the Government of India.¹ A total of 5078 health care workers (41.5%) were unvaccinated.

Figure 1. Figure 1. From January 16th to April 17th, 2021, the vaccination status or timing of positive test results for 506 healthcare workers who tested positive for SARS-CoV-2.

Healthcare workers who tested positive for SARS-CoV-2 after the first dose of the vaccine were those who tested positive at any time between the first and second doses. Healthcare workers who tested positive after receiving the second dose were those who tested positive at any time up to 14 days after receiving the second dose. Breakthrough infection was defined as a positive reaction after the health care worker was considered completely vaccinated (that is, more than 14 days after receiving the second dose). Due to rounding, the total percentage may not be 100.

Since the start of the vaccination program, 506 healthcare professionals have tested positive for SARS-CoV-2. The vaccination status of healthcare workers who tested positive is Figure 1A total of 184 (2.6%) of the 7170 health care workers tested positive after at least one vaccination. The median time between the first dose and a positive response was 44 days (interquartile range, 25-59 days). A total of 72 (2.0%) of the 3650 healthcare workers tested positive after the second dose. The median time from the second dose to a positive response was 20 days (interquartile range, 11-34 days). For healthcare workers who received both doses and completed at least 14 days of follow-up from the second dose, the incidence of breakthrough infections was 1.6% (48 of 3000 healthcare workers). The median time between receiving the second dose and breaking through the infection was 29.5 days (interquartile range, 20-35 days).

Kirtan Lana, MD
Ricin Mohindra, MD
Lakshmi Pinaka, MD
Graduate School of Medical Education, Chandigarh, India
[email protected]

This letter was published on June 2, 2021 on NEJM.org.