16% of fully vaccinated healthcare workers at Kozhikode hospital got infected

A.S. Jayanth KOZHIKODE 25 September 2021 20:37 IST
Updated: 27 September 2021 08:24 IST

None of them, however, required intensive care unit support, says study

Over 16% of healthcare workers at the Government Medical College Hospital, Kozhikode, were found to have symptomatic breakthrough infections even after receiving two doses of the COVID-19 vaccine.

None of them, however, required intensive care unit support, says a first-of-its-kind study in Kerala titled ‘Breakthrough infection following COVID-19 vaccination among healthcare workers in South India’.

The analysis was done by T. Jayakrishnan, Professor, Department of Community Medicine, and Ardra Merin George, junior resident doctor, at the hospital. The peer-reviewed article is slated to be published in Asian Journal of Pharmaceutical and Clinical Research in its October issue. The period of study was between February 27 and June 27.


Breakthrough infections are defined as detection of SARS-CoV-2 virus in a person over 14 days after getting two doses of the COVID-19 vaccine. The Regional Prevention of Epidemic and Infectious Diseases Cell under the department collected data from 737 healthcare workers at the hospital, most of them doctors and nurses. As many as 677 were found to have been vaccinated.

A total of 642 had got Covishield and the rest Covaxin. In the vaccinated group, 144 people had tested positive for the virus before their vaccination. As the recovered persons were immune from reinfection for calculating breakthrough infections, they were excluded from the analysis.

Among the remaining 533 persons, 114 were found to have tested positive even after getting both the doses. Out of this, 89 were symptomatic and tested positive, 14 days after receiving the full course. Eighty-four persons had got Covishield and five others Covaxin. The breakthrough infection rate was found to be 16.7%. All the 89 had any of the mild symptoms such as fever, headache, runny nose, and partial or full loss of smell. Out of this, 36 persons (40.4%) underwent isolation in hospital and 53 persons (59.6%) at home. Combined vaccine efficiency after two doses was found to be 65.7%.

The study says that since healthcare workers are more exposed to COVID-19, the reported breakthrough infections among them may be high. As only persons with symptoms were tested regularly, the actual cases may be under-reported because the asymptomatic never came under the radar. “This was a significant area of concern as most of the breakthrough infections were asymptomatic and were missed. There was also increased probability of transmission to patients and co-workers. It is possible that the infection could be ascribed to virus variants such as Delta which may bypass vaccine-induced immunity,” it says.