Delta Becomes Dominant Variant In NYC, Making Up Two-Thirds Of New Cases

SARS-CoV-2 (round yellow particles) emerging from the surface of a cell cultured in the lab.

SARS-CoV-2 (round yellow particles) emerging from the surface of a cell cultured in a lab. NIAID

The delta variant now accounts for the majority of new COVID-19 cases in the five boroughs, according to data released Thursday from the New York City Department of Health and Mental Hygiene. The offshoot germ rose to become the city’s most common variant in less than five months.

Delta makes up 69% of cases analyzed between June 27 and July 3, the most recent tranche of specimens analyzed by a citywide effort comprising New York City’s Public Health Laboratory, the Pandemic Response Laboratory, hospitals and private clinics. That’s up from 44% of tested cases the week prior. Delta became New Jersey’s predominant strain earlier this week and claimed the national title soon after Independence Day.

The delta variant, which was first spotted in city surveillance in February, is more contagious and more resilient against our immunity defenses compared to the original virus. Pfizer, Moderna and Johnson & Johnson vaccines can still neutralize the delta variant, though it appears more likely to cause breakthrough infections. (On Thursday, a number of New York Yankees players tested positive for COVID-19, reportedly including at least three vaccinated players.)

Delta grew to prominence in New York City as other variants fell, the latter likely tamed by the vaccines.

Read More: Why The Delta Variant Matters If You’re Vaccinated Or Unvaccinated

Based on mounting evidence, full vaccination will protect against severe disease and hospitalization. On Thursday, Los Angeles officials announced that the county would reintroduce its indoor mask mandate for everyone, regardless of their vaccination status.

“The rise of the delta variant in NYC means that now is perhaps the most dangerous time to be unvaccinated,” a city health department spokesperson told WNYC/Gothamist. “All New Yorkers should get a COVID-19 vaccination to protect themselves, their family, and our city.”

Read More: How Parents Can Prepare For The Delta Variant Given Most Kids Are Unvaccinated

Only a small fraction of confirmed COVID cases are tested for virus variants, but the city Health Department says the results generally correspond to citywide trends. Because some samples are tested by hospitals and the medical examiner, the results may skew toward the most severe cases. All recent data reported by the health department is also provisional and may change over time as backlogged cases are assessed.

The findings come as COVID positivity rates rise in some neighborhoods, namely East Harlem and parts of Staten Island. Citywide, the seven-day average of cases increased from 133 on June 20 to 438 on July 12. Hospitalizations and deaths remain at their lowest points, but severe disease has traditionally lagged behind initial infection by a few weeks.