The Heart Care Foundation of India (HCFI) Dr KK Aggarwal Research Fund has reported a unique case of triple infections in a fully vaccinated healthcare worker: two breakthrough infections, which were also both reinfections in a person who already had had an asymptomatic SARS-CoV-2 infection last year.

The patient was a 61-year-old female health care worker in Delhi. She was prediabetic and also had hypertension and chronic bronchial asthma, but no immunocompromised condition.

The first episode happened in August 2020. It was an asymptomatic infection and the patient was under self isolation and home care. The second episode of infection occurred in early April this year. It was the first breakthrough infection and the first reinfection. The line of management was again self isolation and home care. The third episode of infection occurred in late April. It was the second breakthrough infection and the second reinfection. However, this time the patient developed hypoxia and needed hospitalization. The illness lasted for about seven weeks.

The patient was fully vaccinated with Covishield (first dose in February and the second dose in March). Seroconversion had also been documented.

The third episode of infection was at first assumed to be a continuation of the second infection. However, whole genome sequencing revealed it to be an entirely new infection. The first breakthrough infection was found to be due to the alpha variant (B.1.117, first detected in the UK), while the second breakthrough infection was due to the delta variant (B.1.617.2, first detected in India) of SARS-CoV-2 on whole genome sequencing. The Ct values in the Delta variant infection were low enough to suggest transmission potential. The close family member was also found to be infected with the delta variant. The patient is well now and recovering.

Since the patient had three infections, a new term “breakthrough reinfection” was specially coined for this particular case and it is also the first proven case of the same.

Breakthrough infections are being reported in vaccinated persons. A 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 they have completed all recommended doses of a Covid-19 vaccine.

The CDC and ICMR have laid down certain criteria for reinfection.

As per the CDC, the investigative criteria for identifying cases with a higher index of suspicion for reinfection are:

• For persons with / without COVID-19–like symptoms ≥90 daysafter initial infection/illness, and
• For persons with COVID-19–like symptoms 45–89 daysafter initial infection / illness

The time frame given by ICMR is 102 days. It defines re-infection with SARS-CoV-2 as two positive tests at an interval of at least 102 days with one negative RT PCR between the two episodes.

This patient also had a negative test in between the two positive reports and during this period, she was taking care of a fully vaccinated close family member who was a confirmed case of Covid-19. However, this patient developed delta variant reinfection within 19 days after recovery from infection with the alpha variant.

Findings of an ICMR study of post-vaccination breakthrough infections in the country released earlier this month show that around 86% of breakthrough infection cases across the country were due to the delta variant, though there were some alpha variant cases in north India. Only 9.8% delta variant reinfections required hospitalisation and only 0.4% cases were fatal.

It’s not just the viral load; it’s also the variants of concern (VOC), which confer a high risk of breakthrough infection.

The delta variant is a highly transmissible strain with greater affinity to the ACE2 receptors in the lungs. It also shows immune escape. Persons with comorbid conditions are at greater risk of hospitalisation.

Data from the Public Health England (PHE) shows that the risk of reinfection with Delta may be 46% greater than with the Alpha variant.

I do not hesitate to disclose here that the case in point is my case. It has been accepted for publication in “Frontiers in Medicine”, a peer reviewed international medical journal.

And, through this case, I would like to caution everybody to not let down their guard. The pandemic is not over yet. The shadow of the third wave is looming over us. We do not know when it will come? Will it be as ferocious as the second wave? These questions cannot be answered at this point of time.

Breakthrough infections are occurring and most of them are with the VOCs. They can be established only through whole genome sequencing.

A high index of suspicion is needed to investigate potential cases. Covid-19 like symptoms in convalescent or vaccinated individuals should not be ignored.

Covid-appropriate behavior - masks (double masking), physical distancing, hand washing, avoiding crowds - continue to be very important even for the fully vaccinated.

Dr Veena Aggarwal

Consultant Womens’ Health

MD and Chairperson, IJCP Group & Medtalks

Trustee, Dr KK’s Heart Care Foundation of India