The COVID superspreader event at a Linden dance hall underscores the consequences of the faltering vaccination campaign in Arizona.
Reportedly 22 of the 70 people who attended a dance at the hall on May 18 have tested positive for COVID — including perhaps four people who had been at least partially vaccinated. The case demonstrates the continued ability of the pandemic to spawn clusters of infection when people socialize and gather in large groups, especially with close contact, singing and other social activities.
New, faster-spreading variants now dominate in Arizona — mostly the Alpha strain that battered England, but now also the Delta strain that devastated India.
TGen and several university labs sequenced a small sampling of the virus in new cases, with 26,000 samples so far. The Alpha variant accounted for half of the samples for the week of June 21 and the Delta strain for 15%. However, the Delta strain had accounted for just 3% the week before. The sampling is consistent with the experience of other countries, where the Delta strain quickly dominates.
The Alpha strain spreads 60% faster than the original strain — and the Delta variant appears to spread at least 50% more easily than the Alpha.
Both appear more likely to cause more serious illness and death — and the Delta strain appears to infect younger people and children more readily. The Moderna and Pfizer vaccines work against both those strains, especially when it comes to preventing serious illness. Some studies suggest that the protection against infection may drop from 95% to about 80%, but the protection against death and hospitalization remains higher.
State health officials say almost all of the rising number of new cases in Arizona have been among the unvaccinated — including 95% of the 17,000 cases reported in May. Studies show that one shot provides about 40% protection and two shots provide 95% protection. The vaccine appears to provide broader and more long-lasting protection than simply recovering from an infection, so health officials urge even those who have gotten sick and recovered to get vaccinated. Fortunately, growing evidence suggests the current vaccines provide long lasting protection.
Still, reports suggest that four people who got infected at the dance hall had been vaccinated — a surprisingly high percentage compared to the national data. This raises questions about whether those people were infected with a strain that’s better able to evade the protections of the vaccine.
Health officials say the spread of the more virulent strains simply underscores the need to get vaccinated as soon as possible — even if you’ve recovered from an infection.
“It’s all about the percentage of persons that have been vaccinated,” wrote Will Humble, executive director of the Arizona Public Health Association. “One infected person can infect a lot of people in an indoor environment like that with heavy breathing.”
Gila County in the past two weeks has reported 6 cases per 100,000, just below the statewide average but still twice the national average. Hospitalizations in Gila County have declined 8%, with 44% of the population fully vaccinated.
Nationally, the overwhelming majority of new cases, hospitalizations and deaths are now occurring among people who have not been vaccinated.
The Linden dance hall cluster represents one of the few reported cases in which several vaccinated people got infected at the same event. However, the large percentage of unvaccinated people in the dance hall underscores the dangerous lack of vaccinations in the general population.
The federal Centers for Disease Control has said that vaccinated people can mostly go back to normal, but should still avoid crowded, indoor events and settings with lots of unvaccinated people. The CDC has advised people who are not vaccinated to wear masks indoors when they cannot socially distance and to avoid crowded situations.
The CDC reports that a total of 750 fully vaccinated people have died after contracting COVID, but at least 142 of those deaths were not related to the infection. Some 4,000 people have been hospitalized with a breakthrough infection, but 1,000 of those were hospitalized for something other than COVID.
Public health officials are worried that the relatively low vaccination rate among people in their 30s and 40s will prompt many parents to forgo the vaccine for their kids, leading to fresh outbreaks when school restarts in August.
Some evidence suggests the Delta variant more readily infects children and young adults and may cause more serious illness. The Delta strain accounts for about 20% of new cases in the U.S. and has doubled in the past two weeks. Other countries where the Delta strain has become dominant have seen outbreaks in schools and an increase in seriously ill children. The mutations in the Delta virus appear to hide the virus from the fast-acting, front-line immune system cells that dominate immune systems of children. This may give the Delta variant an edge when it comes to infecting children, who have so far been less likely to contract COVID or get seriously ill when they do.
Health officials worry that if parents don’t get their teens vaccinated before school restarts, cases on campus may take off — causing fresh clusters in the community.
Arizona Health Director Dr. Cara Christ said, “People continue to get seriously ill and die from COVID-19, which is tragic when there are safe, highly effective and free vaccines widely available around the state. Having as many people vaccinated as possible will reduce transmission of COVID-19 and in the process reduce the development of variants like Delta. If you have yet to be vaccinated, I hope you’ll do so to protect yourself, your family and your community.”