What there is to know
- Dallas County reaches 80% vaccinated or previously infected milestone to achieve collective immunity.
- Vaccines are still needed to prevent further infections among the unvaccinated.
- Vaccines effective against the Delta variant that doubles every two weeks, according to local officials.
Finally, according to county health officials, Dallas County has been granted herd immunity to the COVID-19 virus. But what does reaching this goal mean?
According to the Centers for Disease Control and Prevention, herd immunity, or community immunity, is “a situation in which a sufficient proportion of a population is immune to an infectious disease (through vaccination and / or previous disease) to spread person-to-person unlikely. “When herd immunity is present, unvaccinated people (such as newborns and people with chronic illnesses) are offered some protection because the disease is unlikely to spread. spread within the community.
Achieving herd immunity in Dallas County meant that 80% of the population had been vaccinated against the virus or had already been infected with the virus and therefore had antibodies to prevent further infection.
In February, the Parkland Center for Clinical Innovation (PCCI) initially predicted that herd immunity would be reached in mid-June. However, a slowdown in COVID-19 vaccinations forced the forecast to be revised at the end of July. PCCI and DCHHS launched a dashboard this week to track collective immunity.
The milestone was crossed this week, a little earlier than the last forecasts. From Wednesday July 7 The Dallas County Health and Human Services / PCCI dashboard indicated that 80.4% of the population Now meets the criteria of having been infected or having been vaccinated and, as a result, the county has achieved collective immunity.
It’s important to remember that while herd immunity may offer greater protection to a community, it does not guarantee that people will not continue to be infected with COVID-19.
Parkland’s chief medical officer Dr Joseph Chang told NBC 5 Wednesday afternoon that herd immunity essentially means 8 out of 10 people in the county should not be able to contract the coronavirus.
Chang added, however, that some age groups are more protected than others. Older groups have around 90% herd immunity, while some younger and more vaccine resistant groups may be only 40% protected. Children under 12, who cannot yet be vaccinated, remain at risk of infection.
PCCI CEO Steve Miff said in a statement Wednesday that while collective immunity “represents good progress” in the community, “it is important that we understand that the job is not done.”
“While the entire community has averaged the 80% mark, there are only 49 postcodes above the 80% threshold with 45 postcodes still below the 80% mark.” Miff said in a statement Wednesday. “There are still large pockets in the community that remain vulnerable. “
There is a lot of talk these days about how collective immunity will be our ticket out of the pandemic. Here’s what you need to know about what collective immunity is and how we get it.
Experts like Chang and Miff always encourage those who are not vaccinated against the virus to get vaccinated as soon as possible.
“These vaccines are extremely effective even against all these new variants that are coming out, whether it’s the Delta or the new Lambda that everyone is talking about,” Chang said. “We know that these vaccines from Pfizer and Moderna are very effective in preventing hospitalizations and deaths and that is, of course, the most important thing.”
Chang said patients hospitalized at Parkland for COVID-19 are now almost exclusively younger people, and not all of them are vaccinated.
“The Delta variant is here, it’s making people sick and you know what? It’s those 30 and 40 years that are getting sick,” Chang said. “Right now, in my hospital, if you take a look at February, all of the COVID admissions, none of the people who were admitted to my hospital with COVID have been vaccinated. That’s the power of vaccination. . “
How is collective immunity calculated
DCHHS calculates herd immunity using the number of confirmed, probable and projected cases of COVID-19 plus the number of people who received at least one dose of the vaccine, minus an estimated overlap.
The county health department dashboard showed on Wednesday that 1.21 million people in the county had received at least one dose of the vaccine (44.19%) and that 989,000 people had completed a full cycle. The DCHHS dashboard also showed that there were 306,000 confirmed and probable cases of the virus since March 2020.
The PCCI said the calculations used to measure the immunity heard tracked data at the individual level for vaccinations given and COVID test results since the start of the pandemic. For people infected, but not tested, there is an adjusted incidence rate ratio of 4x [AIRR] for the adult population and 5x for the pediatric group based on national and local seroprevalence data. The model also calculates an overlap of 28% of the vaccinated population of Dallas who would have had a previous infection with COVID-19 and have recovered.
The PCCI said the current Delta variant is expected to account for about 25% of COVID-19 cases locally, doubling about every two weeks. Within a month, the PCCI said, that could put the Delta variant in the range that caused a new wave of infections in the UK, despite their estimated immunity being below the herd immunity threshold for Delta.
The significantly higher viral loads and the more infectious nature of the Delta variant could raise the herd immunity target up to 88% to suppress peaks of infection when the Delta variant becomes the dominant variant within a few weeks.
The PCCI said the message is simple, don’t wait to get the vaccine.
“For those who are still hesitant, the safety and efficacy studies to date are overwhelmingly positive. There are also two key milestones ahead that should give those who remain hesitant more confident: full FDA approvals for mRNA vaccines expected in the coming weeks and approval for the under 12 age group. in the fall, “Miff said in a statement.