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Revista de investigación clínica

versión On-line ISSN 2564-8896versión impresa ISSN 0034-8376

Rev. invest. clín. vol.74 no.6 Ciudad de México nov./dic. 2022  Epub 23-Ene-2023 

Letter to the editor

SARS-CoV-2 Reinfection Rate in Vaccinated Hospital Workers: Correspondence

Rujittika Mungmunpuntipantip1  * 

Viroj Wiwanitkit2 

1Department of Consultant Unit, Private Academic Consultant, Bangkok, Thailand;

2Department of Community Medicine, Dr. DY Patil University, Pune, Maharashtra, India

Dear Editor,

We would like to share ideas on “Significant Rise in SARS-CoV-2 Reinfection Rate in Vaccinated Hospital Workers during the Omicron Wave: A Prospective and Cohort Study1.”Despite a high primary vaccine coverage rate, Ochoa-Hein et al. reported that the SARS-CoV-2 reinfection rate increased considerably during the Omicron wave1. Nearly one-third of the reinfected workers had a booster shot around 14 days before the most-recent COVID-19 event, according to Ochoa-Hein et al.1. We both believe that the rate of reinfection in workers who had received vaccinations during the Omicron wave may have changed2. It would be interesting to discuss how vaccination rates are related. The high rates of vaccination and COVID-19 reinfection may or may not indicate that the vaccine is effective in preventing the disease2. There are many variables2. The type of vaccine and the administration route may be crucial topics to discuss3. In addition, as COVID is a common clinical entity, it is possible that some workers may have had the condition in the past asymptomatically4. In some circumstances, the reaction to a booster shot and the risk of reinfection may change. The workers’ general state of health is still another crucial consideration. It is difficult to draw an exact conclusion without all the data.


1. Ochoa-Hein E, Leal-Morán PE, Nava-Guzmán KA, Vargas-Fernández AT, Vargas-Fernández JF, Díaz-Rodríguez F, et al. Significant rise in SARS-CoV-2 reinfection rate in vaccinated hospital workers during the Omicron wave: a prospective cohort study. Rev Invest Clin. 2022;74:175-80. [ Links ]

2. Araf Y, Akter F, Tang YD, Fatemi R, Parvez MS, Zheng C, et al. Omicron variant of SARS-CoV-2: genomics, transmissibility, and responses to current COVID-19 vaccines. J Med Virol. 2022; 94:1825-32. [ Links ]

3. Kashte S, Gulbake A, Iii SF, Gupta A. COVID-19 vaccines: rapid development, implications, challenges and future prospects. Hum Cell. 2021;34:711-33. [ Links ]

4. Joob B, Wiwanitkit V. Letter to the editor: coronavirus disease 2019 (COVID-19), infectivity, and the incubation period. J Prev Med Public Health. 2020;53:70. [ Links ]

Received: September 11, 2022; Accepted: October 07, 2022

* Corresponding author: Rujittika Mungmunpuntipantip E-mail:

Author's reply

Author’s reply to SARS-COV-2 Reinfection Rate in Vaccinated Hospital Workers: Correspondence

Eric Ochoa-Hein3 

Patricia E. Leal-Morán3 

Karen A. Nava-Guzmán3 

Abril T. Vargas-Fernández3 

José F. Vargas-Fernández3  * 

Fabricio Díaz-Rodríguez3 

Joel Armando Rayas-Bernal3 

Ricardo González-González3 

Pavel Vázquez-González3 

Martha A. Huertas-Jiménez3 

Sandra Rajme-López3 

Pilar Ramos-Cervantes3 

Violeta Ibarra-González3 

Luis A. García-Andrade3 

Fernando Ledesma-Barrientos3 

Alfredo Ponce-de-León3 

José Sifuentes-Osornio3 

Arturo Galindo-Fraga3  * 

3Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico

Dear Editor:

We thank Drs. Mungmunpuntipantip and Wiwanitkit for their thoughtful observations. Indeed, as stated in our report, we acknowledge some limitations in our study. Nonetheless, our conclusions generally agree with what has been reported recently by other authors. The ability to evade immunity (due to either previous infection or vaccination) is an important factor leading to infection with the Omicron variant1. Our data agree with those of others in that current vaccines have lower effectiveness for preventing both infection and disease by the Omicron variant of SARS-CoV-22, irrespective of other variables. At the time of our study end date, booster shots were being given to the Mexican adult population, and it was acknowledged that additional study of their effects was warranted. On further analysis of our database, we found that 36.7% of healthcare workers with only one episode of infection had received a booster ≥14 days before the infection episode (not reported), as compared to 30.1% of those with a reinfection (non-significant difference). Thanks to recent studies, we now know that booster shots are able to restore immunity at least partially3 and are currently recommended.

The question of whether vaccines were effective or not in preventing disease (particularly reinfection) in our setting is interesting and deserves further study, albeit this was beyond the scope of the present work. However, we were able to show that the previous vaccination did not guarantee full protection against reinfection during the Omicron wave, in part because of waning of immunity4 (a median of 323 days had elapsed between the reinfection episode and the last vaccine dose). It would have been interesting to study if different vaccine schemes were related to different reinfection rates. We were only able to inform that the great majority of our healthcare workers had a heterologous vaccination schedule with two doses of BNT162b2 followed by one dose of ChAdOx1-S, and that all healthcare workers were vaccinated through the parenteral route (no other routes of administration have been used in Mexico). A recent study showed that mRNA vaccines are apparently associated with the best immunogenic responses5, but to the best of our knowledge, we ignore if this particular vaccine platform performs clinically better against the Omicron variant and subvariants as compared to other vaccine platforms, since there are no head-to-head comparative studies6.

As Drs. Mungmuntipantip and Wiwanitkit pointed out, the lack of data regarding the state of health of our healthcare workers is a weakness. Thus, we were not able to relate the presence or absence of various comorbidities to the reinfection rate.

Our study does not inform the risk of reinfection after an asymptomatic past infection, and this must be studied further; however, failure to detect and record asymptomatic infections biases toward an even higher underestimation rate, was acknowledged appropriately.


1. Lyngse FP, Mortensen LH, Denwood MJ, Christiansen LE, Møller CH, Skov RL, et al. Household transmission of the SARS-CoV-2 Omicron variant in Denmark. Nat Commun. 2022;13:5573. [ Links ]

2. Buchan SA, Chung H, Brown KA, Austin PC, Fell DB, Gubbay JB, et al. Estimated effectiveness of COVID-19 vaccines against Omicron or Delta symptomatic infection and severe outcomes. JAMA Netw Open. 2022;5:e2232760. [ Links ]

3. Menni C, May A, Polidori L, Louca P, Wolf J, Capdevila J, et al. COVID-19 vaccine waning and effectiveness and side-effects of boosters: a prospective community study from the ZOE COVID study. Lancet Infect Dis. 2022;22:1002-10. [ Links ]

4. Ridgway JP, Tideman S, French T, Wright B, Parsons G, Diaz G, et al. Odds of Hospitalization for COVID-19 After 3 vs 2 Doses of mRNA COVID-19 Vaccine by Time Since Booster Dose. JAMA. 2022;328:1559-61. [ Links ]

5. Sablerolles RS, Rietdijk WJ, Goorhuis A, Postma DF, Visser LG, Geers D, et al. Immunogenicity and reactogenicity of vaccine boosters after Ad26.COV2.S priming. N Engl J Med. 2022; 386:951-63. [ Links ]

6. Andrews N, Stowe J, Kirsebom F, Toffa S, Rickeard T, Gallagher E, et al. Covid-19 vaccine effectiveness against the Omicron (B.1.1.529) variant. N Engl J Med. 2022;386:1532-46. [ Links ]

* Corresponding author: Arturo Galindo-Fraga E-mail:

Creative Commons License Instituto Nacional de Cardiología Ignacio Chávez. Published by Permanyer. This is an open access article under the CC BY-NC-ND license