COVID-19 vaccination and breakthrough infections among healthcare workers: an online survey

INTRODUCTION

Coronavirus disease is an infectious disease caused by a new coronavirus SARS-CoV-2. This disease was first reported in Wuhan, the largest metropolitan area in China’s Hubei province, in December 2019.¹ It was declared as a public health emergency of international concern on January 30^th 2020 and as a pandemic on March 11^th 2020.² Currently there have been over 180,000,000 cases of the COVID-19 disease reported and over 4,000,000 deaths.³

The widespread infection and the morbidity and mortality associated with COVID-19 has triggered a tidal wave of vaccine developments. Within the first 9 months of the advent of the virus, there were 200 vaccine candidates out of which 36 had entered clinical trials.^4,5 Some of the prominent ones include mRNA vaccine- 1273 (Moderna TX, Inc) and BNT162b1 (BioNTech FosunPharma, Pfizer), vector virus Sputnik vaccine and ChAdOx1 (University of Oxford) and Killed whole virus vaccine-Covaxin (Bharat Biotech).^6-10 The efficacy of the vaccines varied between 66.7% (Oxford university), 81% (Covaxin), 91.6% (Sputnik) 94.10% (Moderna) and 95% (Pfizer).^6-10

Housing a population of 1.38 billion, the COVID-19 phase-1 vaccination drive in India covering health care workers and frontline workers started on 16^th January, 2021.¹¹ The vaccine programme was initiated with the vaccines Covishield (by Serum Institute of India Ltd) and Covaxin (by Bharat Biotech International Ltd).¹² Subsequently the elderly, people above 45 years of age and lastly people above 18 years were included in the vaccination program.¹³

The COVID-19 vaccines greatly provide protective immunity against severe disease and death. The vaccines do not prevent infection and COVID-19 disease is seen in vaccinated individuals.^14-21 Another factor to be considered is the ‘Peltzman effect’ where people are more likely to engage in risky behaviours when safety measures are mandated. Following vaccination, people might get a false sense of security causing them to get lax about other public health and social measures like social distancing and wearing of masks. This study explores the possibility of COVID-19 infection following vaccination. The objective of the study is to assess the risk of COVID-19 breakthrough infections among vaccinated individuals and to describe the COVID appropriate behaviour followed by vaccinated individuals.

METHODS

A descriptive cross-sectional online study was conducted among healthcare workers (HCW) from across India during May 2021. Snowball sampling technique was followed for the selection of the health care workers, i.e., one vaccinated individual will in turn identify another health care worker and pass on the questionnaire. HCWs aged between 18 years and above, had received at least one dose of COVID-19 vaccine were eligible to participate in the study. A total of 413 responses were generated, after data cleaning 393 were included for the final analysis. The sample size was calculated based on the feasibility and constraints in conducting the study. The health care workers included medical doctor, dental doctor, medical students, staff nurse, lab technicians and pharmacy. They worked in various settings like dedicated COVID hospitals, dedicated COVID health centres, COVID care centres (DCH/DCHC/CCC), medical colleges, nursing homes and individual clinics.

The data was collected online using Google forms. The questionnaire was semi-structured with both open and closed-ended questions, and captured details of age, workplace exposure, existing comorbidities, days after vaccination, type of vaccine, status of vaccination etc.

Inclusion criteria

Health care workers with access to the internet and tech savvy were included.

Exclusion criteria

Immuno-compromised, chronically ill and deceased vaccinated individuals were excluded from the study.

Operational definitions

Covid19 vaccine breakthrough infection, is defined 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 an FDA-authorized COVID-19 vaccine.²²

COVID-19 disease was described as mild, moderate and severe based on the definition given by ICMR (mild: upper respiratory tract infection symptoms with no shortness of breath or hypoxia; moderate: respiratory rate ≥24/minute, breathlessness or SpO₂ 90% to ≤93% on room air; severe: respiratory rate >30/minute, breathlessness or SpO₂<90 % on room air).²³

RESULTS

A total of 393 health care workers in the age range of 18 to 74 years with median age 26 (IQR-17, 21, 38) years were included. 214 (54.5%) were males, 177 (45.1%) females and 2 (0.5%) others as described in Table 1. Majority 334 (85%) health care workers were in the age range of 18-45 years.

227(65.6%) of the health care workers were doctors, 121 (30.7%) were medical students and 45 were dental doctors, nurse and paramedical staff. 219 (55.8%) were working in CCC/DCH/DCHC either in the OPD, wards, ICU, fever clinics, triage centre and vaccination centre. 61(15.5%) were working in non-covid hospitals either in OPD, wards, ICU, fever clinics, and vaccination centres. 78 (19.8%) were medical students and 35 (8.9%) worked in dental colleges and clinics.

344 (87.5%) health care workers (HCW) were fully vaccinated and 49 (12.5%) were partially vaccinated. Majority 357 (90.8%) HCW had taken Covishield and 36 (9.2%) had taken Covaxin.

The median number of days after vaccination was 60 (IQR 41, 84). The minimum and maximum number of days after vaccination was 1 and 120 days. Majority 261 (66.4%) HCW had completed more than 45 days after vaccination followed by 83 (21.2%) 16-45 days after vaccination.

26 (45.6%) HCW were overweight/obese, 11 (19.3%) had diabetes mellitus, 17 (29.8%) had hypertension, 3 (5.3%) hypercholesteremia, 2 (3.5%) hypo/hyperthyroid, 7 (12.3%) asthma/seasonal allergy, 2 (3.5) neurological problems and 1 (1.8) neurological problem. After COVID-19 vaccination, majority 382 (97.2%) always wore the mask, 386 (93.6%) did hand sanitization and 357 (90.8%) practiced social distancing.

Figures in parenthesis indicate percentage

Out of the 393 vaccinated health care workers, 57 (14.5%, CI 0.11-0.18) subjects had COVID-19 disease (breakthrough infection) after vaccination. Majority 37 (64.9%) were in the age group of 18-30 years. There was no statistically significant association after vaccination between the COVID-19 disease and no disease. The median age was 25 (IQR 20, 36) years and the age range was between 1-70 yrs. 43 (75.4%) were fully vaccinated and 14 (24.6%) were partially vaccinated as described in Table 2. Majority 31 (54.3%) were females and 26 (45.7%) were males. 43 (75.4%) worked in DCH hospital, 11 (19.3%) were medical students and 3 (5.3%) were dentists. Majority 35 (81.4%) and 8 (57.1%) had mild symptoms in the fully and partially vaccinated groups and was statistically significant (z=5.82, <0.05). 48 (84.2%) had no comorbidities and 5 (8.8%) were obese/overweight.

There was no statistically significant association between the type of vaccine [Covishield (14.5%) and Covaxin (13.8%)] taken and covid19 disease (χ²=0.09, p=0.9).

A vast majority had continued to wear masks (97.0% and 98.0%), sanitize hands (93.0% and 98.0%) and followed social distancing (91.6% and 86%) in both fully and partially vaccinated groups.

26 (45.6%) primary contacts of the vaccinated and positive cases developed COVID-19 disease, 17 (29.8%) did not know and 14 (24.6%) did not develop the disease.

DISCUSSION

The study focused on HCW as they are the frontline in management of COVID-19 and more exposed than the general population. Majority of the subjects in the study are below 45 years, doctors and working in DCH/DCHC/CCC. Females were more compared to males. This could be due to the snowball sampling and younger professionals being more tech savvy in answering the online questionnaire.

The majority of the HCW were fully vaccinated as they were most vulnerable and were rightly the first to receive the vaccine. However, it was disheartening to observe that about 10% were yet to be fully vaccinated even after 5 months of commencement of vaccination drive in India indicating vaccine hesitancy. A study in rural areas of Bangalore had observed that about 20% had vaccine hesitancy.²⁴ A study from Arab region showed a significant rate of vaccine hesitancy among Arabs in and outside the Arab region (83% and 81%, respectively).²⁵

Female participants, 30-59 years-old, those without any chronic diseases, lower-level of academic education, and those who do not know the type of vaccine are more hesitant to receive COVID-19 vaccination in study done in and outside the Arab region.²⁵ The most cited reasons for hesitancy are concerns about side effects and distrust in healthcare policies, vaccine expedited production, published studies and vaccine producing companies.²⁵

Maximum proportion of subjects had taken covishield as expected with Serum institute of India being the largest suppliers of COVID-19 vaccine in India. The Department of biotechnology had recently informed the parliamentary standing committee on science and technology, environment, forests and climate change that the estimated manufacturing capacity of Covishield is 70-100 million doses every month, while Covaxin has a planned production capacity of 12.5 million a month.²⁶

45 days after two doses of vaccination is said to protect against the disease. The fully vaccinated people who developed the disease were infected mostly between 0-45 days after the vaccination dose (53.5% of fully vaccinated subjects). This is similar to another study in Israel where the median interval between second vaccination dose and detection of infection was 39 days.¹⁴

The type of vaccine administered and breakthrough infection was not significant in the current study. It was observed that people were infected irrespective of the type of vaccine given.¹⁴ Similar studies conducted in UK, New Delhi, Chicago and Bangalore observed that the breakthrough infections varied between 0.2-13.27% irrespective of the vaccine administered.^15-18

Two separate studies conducted by AIIMS and NCDC showed that it was possible for the delta strain of SARS-Cov-2 to be able to escape antibodies produced by 2 doses of both Covishield and Covaxin^,.²⁷

Majority experienced mild symptoms similar to the observation of the current study. The vaccine protects against severe forms of the disease similar to the findings from a study in the UK.^15,19-21

Another study that was conducted in Odisha found that out of 274 fully vaccinated individuals with breakthrough infections 9.9% required hospitalization.¹⁹ Older individuals showed lesser odds of symptoms continuing for more than 28 days.¹⁵ In a study conducted by CMC, Vellore, 2 doses of vaccination provided a protective effect of preventing infection by 65%, hospitalization by 77%, need for oxygen therapy by 94% and need for ICU admission by 94%.²⁰

Similarly in the US, out of 10,262 reported breakthrough infections from 46 states, only 27% were asymptomatic and only 10% were hospitalized (29% of whom where asymptomatic or hospitalized due to non-COVID-19 reasons).²¹

A negligible few had discontinued COVID appropriate behaviour after getting vaccinated like wearing of mask, hand sanitization and social distancing, while majority followed COVID appropriate behaviour which was a good sign to observe in the current study.

About 50% of the vaccinated COVID-19 positive HCWs’ primary contacts had developed COVID-19 implying that it is important to continue the practice of COVID appropriate behaviour even after vaccination. Moreover HCW, by virtue of their profession, are at an increased risk of developing COVID-19.²⁸

The present study observed that breakthrough infections occurred irrespective of the place work i.e., DCH/DCHC/CCC. The HCWs informed that they had followed COVID appropriate behaviour and still breakthrough infection was observed telling us about the importance to continue with the strictest COVID appropriate behaviour while working in the hospital.

This study has some limitations. As this was an online questionnaire, we assume that the subjects were speaking the truth. The snowball sampling technique may be biased and may not be giving the true information. The sample is not a true representative of health care workers across India. This study does not take into account the number of deaths that have occurred due to breakthrough infections following vaccination as it is beyond the scope of the study.

CONCLUSION

One tenth of the health care workers had breakthrough COVID-19 infection post vaccination. Majority had mild symptoms and occurred irrespective of type of vaccine administered.

Recommendations

COVID-19 vaccines are safe and prevent severe forms of COVID-19 disease. Mass vaccination of the public will bring down the burden of COVID-19 disease in the community.

ACKNOWLEDGEMENTS

The authors thank all the doctors, interns, frontline workers and medical students who have taken part in this study.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: Not required

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