The hospital’s Infection Prevention and Control Unit conducted active and passive surveillance of vaccinated staff by using daily health questionnaires, hotlines, on-call infectious disease unit staff, and post-vaccination web-based questionnaires to identify and test symptomatic HCWs. Among 4,081 HCWs vaccinated in the first week of the campaign, 22 (0.54%) later had laboratory-confirmed COVID-19 (Table). The average age among COVID-19–positive vaccinated HCWs was 45.3 years (±9.85 years), and they belonged to different healthcare sectors and worked on various wards.

Among the 22 vaccinated HCWs who tested positive for COVID-19, 13 were tested because they had symptoms, most commonly an influenza-like illness that included fever, chills, cough, headache, myalgia, and sore throat. Two vaccinated HCWs were tested because of exposure to confirmed or suspected COVID-19 cases and because they reported symptoms upon questioning. Asymptomatic COVID-19 cases were identified among HCWs as part of postexposure screening. Among the 22 COVID-19–positive HCWs, 11 had presumable community-related exposures, 4 of whom reported exposure incidents that occurred before or on the date of vaccination. An investigation conducted by the hospital’s Infection Control and Prevention Unit identified 10 healthcare-related secondary exposures. However, we did not identify any point-source exposures or COVID-19 clusters linked to the immunization process.

Among the 11 vaccinated HCWs who reported COVID-19 symptoms, the median time between the first dose of BNT162b2 immunization and symptom onset was 3.5 (range 0–10) days; we excluded 1 vaccinee from our calculation and analysis because the HCW had symptoms before immunization (Table). The median time between the onset of symptoms and testing was 1 day, demonstrating the high level of suspicion for COVID-19 during the vaccination campaign.

Of note, apart from the need for early detection, persons who test positive for COVID-19 after receiving the first vaccine dose (whether asymptomatic and tested following exposure or tested because they are symptomatic) are not eligible to receive the second dose, according to Ministry of Health policy. However, depending on availability of vaccines, this policy might change when further data are collected.

COVID-19 in HCWs is a major concern for health authorities worldwide. HCWs, especially acute and chronic care facility personnel, are at high risk for contracting symptomatic and asymptomatic COVID-19 and might become infected at home or nosocomially while caring for patients or interacting with other staff members (5–7). Infections among HCWs have an immediate effect on their close occupational environment and the overall healthcare system. Secondary exposures, isolation, and infections of staff can substantially impair the capacity of a single ward to care for patients, creating a snowball effect with collateral damage to both the functional resilience of the facility and morale of staff. Consequently, as soon as COVID-19 vaccines were deployed in Israel, HCWs were the first group to receive it.

We report 22 cases of early, postimmunization, laboratory-confirmed COVID-19 among HCWs during the launch of the vaccination campaign in a large hospital in Israel. BNT162b2 is not likely to exert protection against clinical disease during the first days after receipt of the first dose. Efficacy of the BNT162b was 52% a week after the first dose, and positive COVID-19 cases were described among vaccinees even early after the second dose (8). Thus, during a large-scale immunization campaign coinciding with rapid national increase in COVID-19 cases, some immunized persons likely will develop clinical disease.

The co-occurrence of vaccination deployment with the rapidly climbing COVID-19 spread in many parts of the world is a confusing period in which hope is mixed with great vulnerability. The phenomenon of pandemic fatigue, in which the population tires of constant safety precautions, testing, isolation, and restrictions, could lead to less social distancing and personal protection. Pandemic fatigue coupled with the availability of a vaccine, might give the population a false sense of reassurance and consequently lead to a brisk increase in COVID-19 cases. Thus, almost every physical complaint after vaccination poses a true diagnostic dilemma as to whether an adverse reaction or a new COVID-19 infection is the cause. Undetected COVID-19 cases among HCWs could be hazardous for patients and other staff.

Clinicians should have a high level of suspicion of reported symptoms and avoid dismissing complaints as vaccine-related until true infection is ruled out and vaccinees are tested. Active and passive surveillance schemes that enable rapid testing and initiation of infection control measures are essential in preventing possible diagnostic delays and secondary exposures. Therefore, healthcare-related indications for testing should not be altered until systematic and exhaustive data are gathered regarding vaccine effectiveness in healthcare settings.