If all goes according to plan, a large portion of California could come close to herd vaccination levels by late summer. Within a few weeks, the consequences can be dramatic: very low cases, people can get back together comfortably, maybe even a few looser rules around wearing a mask.
Of course, few stuck to this pandemic at the plan.
Between the emergence of new coronavirus variants, unreliable stock of vaccines and uneven access to the available doses, it can take months or even years longer than someone wants to hit the herd immunity. It is possible that California, the country and the world will never get there.
That would be unfortunate, but not necessarily disastrous. The vaccines that are available are very good at preventing serious diseases, even with the variants that seem somewhat resistant, and it can be readjusted to suit the virus as it changes. Vaccinations are likely to reduce hospitalizations and deaths due to COVID-19, and this could make the pandemic much more tolerable in the coming months, long before it is technically over.
‘I hope that by early summer we will be vaccinating the general public in a broader perspective. And we must see correspondingly wonderful consequences by early autumn, ‘said dr. Catherine Blish, an expert infectious disease at Stanford, said.
Blish is still optimistic about herd immunity – even though she, like most of her peers, has no idea how long it will take to get there. “The most important thing to remember is that we have to be patient,” she said.
Herd immunity occurs when enough of a population is immune to a virus that can no longer spread it. Measles is a good example: enough people in the United States are vaccinated that the virus only causes a problem when cases are brought in from other countries and accidentally reach communities vaccinated below, leading to local outbreaks.
Hours are used to track each vaccinated person during a pop-up vaccination clinic in the Gilroy Senior Center.
Stephen Lam / The ChronicleIt is not clear how many people need to be vaccinated to achieve herd immunity with the coronavirus; Dr Anthony Fauci, the country’s leading expert in infectious diseases, estimates 70% to 85%. But it is a gripping target, based on how protective vaccines are against new variants and other factors, including the effectiveness of the vaccines on children and how long immunity lasts. Children are unlikely to be eligible for shots early next year, but studies have found that they do not drive the pandemic.
Regardless of the final percentage and if the vaccine is accepted to be more reliable, many parts of the US could come close to herd immunity within six to eight months.
Along the way, provinces must see a steady, significant decline in hospitalizations and deaths. Some experts believe that the vaccines are already helping, with fewer outbreaks in nursing homes in particular. The consequences should become clearer in the next month as provinces continue to reopen the economy and hospitalizations do not rise again – although there is a new increase in cases as more contagious variants gain traction, health officials warn.
Once communities achieve herd immunity, new cases must fall rapidly. If the Bay was an island, after vaccinating about 80% to 90% of the inhabitants, the pandemic could be over within two weeks, said dr. George Rutherford, an expert on UCSF infectious diseases, said.
But global ties mean the coronavirus, even after the region, or even the country, reaches herd immunity levels, will remain a threat – but a less life-changing one. If communities can only take matters down to a handful per day, they can quickly isolate and contain new infections that are imported and prevent outbreaks.
‘How would we live if there were 10 to 20 cases a day or even 100 cases a day in the United States? We will enjoy life considerably, ”said dr. John Swartzberg, an expert in infectious disease in UC Berkeley, said. The US currently reports more than 50,000 cases per day. “This is where we can get away with herd immunity.”
Assuming that herd immunity is achievable, there are various variables that can delay it. One unknown is how long immunity lasts after people are vaccinated. Some infectious disease experts fear that immunity may decline within a few months, which means that the first round of people to be vaccinated need boosts before the final groups receive a single dose. But most experts believe immunity probably lasts longer than that, maybe years.
Variants can complicate things and can even make the immunity of the herd an impossible target if the virus mutates too quickly so that the vaccine cannot survive. But even in that case, the vaccines would probably prevent the most serious diseases, and the coronavirus could end up similar to flu, in terms of how it affects daily life and the impact on healthcare systems.
The most important variants so far come from South Africa and Brazil, both of which have been identified in small numbers in the United States; two cases of the variant from South Africa were found in the Bay Area. These variants reduce the effectiveness of vaccines, and it may also evade the natural immunity against previous infection. This may mean that more people need to be vaccinated, or that they need to be promoted for the population to achieve herd immunity.
‘The current vaccines will still make a dent. They may not necessarily be able to pinpoint the 95% efficiency, ”said Shannon Bennett, head of science at the California Academy of Sciences. “But I’ll take 60% in a heartbeat.”
The greater concern with variants is what is to come – if those who have already emerged are able to partially evade vaccines, what happens if future variants escape completely? This reasoning is part of the rush to get as many people vaccinated as quickly as possible, because the less the virus can circulate, the less it can turn into something more dangerous.
The vaccine explosion was notorious in the United States. Many provincial and city leaders said they have staff and other resources to reach almost everyone by the end of the summer. But these plans are based on supply, which is on the rise but has been hampered by everything from government disorganization to winter storms. It is also unclear what part of the population will drop to take the vaccine, even if it is eligible.
Many public health experts call for prioritizing vaccination for communities hardest hit by the pandemic. Concentrating on two neighborhoods is important for two reasons: to protect the people who have suffered the most and to speed up the climb to herd immunity.
“You want your vaccinations to break the cycles of transmission,” said Dr. Kirsten Bibbins-Domingo, vice dean for population health and health equity at UCSF, said. “The virus did not hide. We know where it was. So go there and grab everyone in there. ”
‘The slow explosion of the vaccine, the emergence of the variants and then this extremely uneven distribution, really makes me think that in the short term, or maybe ever, we will not achieve effective herd immunity.’
Public health officials said they were aware of the need to vaccinate communities with the highest cases, and many provinces have opened clinics in the neighborhoods. Last week, health officials opened a one-day-a-week pop-up vaccination clinic in Gilroy, which has the highest infection rate in Santa Clara County.
Gilroy resident Patricia Lugo, 57, showed up Wednesday with her 83-year-old mother so they could both be vaccinated; Lugo qualifies as her mother’s primary caregiver. Lugo said she isolated them extremely to prevent infection, but she was nervous about the vaccine being so new and about side effects. She made two previous appointments for the shot and canceled.
The arrival of the variant from South Africa in the Bay finally convinced her. In addition, she wants to set an example for her four adult sons, who have reservations about being vaccinated. She knows that until she is all vaccinated, she cannot embrace her children and grandchildren. And also her community can not recover.
“I want everyone to get it so we can all be safe and have our lives back to normal,” Lugo said a few minutes after getting her first shot. “Today I have decided to overcome my fear. This is what I have to do. ”
Erin Allday is a staff writer for the San Francisco Chronicle. Email: [email protected] Twitter: @erinallday