Majority of breakthrough cases on Guam had Pfizer vaccination

Pfizer's COVID-19 vaccine. (PNC file photo)

Most of the breakthrough COVID cases on Guam were among those vaccinated with the Pfizer vaccine.

This was one of the findings revealed by epidemiologist Dr. Ann Pobutsky during her weekly media briefing held Thursday morning.

According to Pobutsky, from Feb. 7, 2021, to Oct. 7, 2021, there have been 2,859 “breakthough” cases among people who were fully vaccinated and subsequently tested positive.

The majority of these were Pfizer vaccinated (64.9%), followed by Moderna (26.4%) and Johnson & Johnson (6.4%) with 2.3% unknown (DoD).

According to Pobutsky, unvaccinated persons continue to be the majority of infected cases in the population. However, breakthrough cases through the surge have sustained a similar case rate.

The rolling average of cases continues to fall at a slow and steady pace and is currently at 118 cases per day on the Seven Day Rolling average.

The CAR Score, although continuing to fluctuate between 20-25, is in total downward trend as well.

“We are starting to observe a decrease in the number of tests that are being performed daily to less than 1000 tests per day, with the same positivity rate. The hospital numbers continue to decrease, while the ICU numbers remain the same, with deaths continuing but decreasing. We have finally reached 80% of the eligible population (12+) being fully vaccinated, which only includes civilian data not inclusive of the DoD vaccinated numbers,” Pobutsky said.

The breakthrough cases were evenly distributed among males (50.7%) and females (49.3%), with the majority of breakthrough cases occurring among those ages 18-39 (42.6%) and those 40-59 (35.1%), which are also the main age groups of positive cases during the surge.

There were 15.4% breakthrough cases among those aged 60-74, 4.3% among those age 12-17, and 3.6% among those ages 75 or older.

The average number of days between final vaccination dose and receipt of a positive test was 146.29 days or 4 and one-half months.

As of Oct. 1, 2021, there were 137,105 fully vaccinated civilians, with 2,793 civilian “breakthrough cases” or 2%.

Among deaths up to Oct. 1, 2021, fully vaccinated were 13% (all of whom had multiple co-morbidities).

“As noted in previous reports the patterns observed during Guam’s surge from July 2021 to the present are consistent with what would be expected with the Delta variant of COVID-19 — increasing numbers of breakthrough cases as well as increasing numbers of asymptomatic cases, along with high numbers of deaths in August and September, particular Dead on Arrival,” Pobutsky said.

Sequencing results from the CDC now confirm that Delta has been circulating on Guam. Sequencing results received on Oct. 8, 2021, show that of the 67 samples sent to CDC from July 25, 2021 to Aug. 10, 2021, 59 were Delta (B.617.2) or Delta AY variants (88%).