If everything goes according to plan, much of California could come close to the collective immunity levels of vaccination in late summer. In weeks, the effects can be dramatic: very low case rates, people allowed to meet comfortably again, perhaps even some more flexible rules on wearing masks.
Of course, little about this pandemic followed the plan.
Between the emergence of new coronavirus variants, unreliable vaccine supplies, and unequal access to available doses, it could take months or even years longer than anyone would like to achieve collective immunity. It is possible that California, the nation and the world will never get there.
That would be unfortunate, but not necessarily disastrous. The vaccines available are powerfully good at preventing serious diseases, even with variants that appear to be somewhat resistant, and can be retrofitted to match the mutated virus. Vaccines will almost certainly reduce hospitalizations and deaths from COVID-19, and that could make the pandemic much more tolerable in the coming months, long before technically ending.
“I am hopeful that we will be vaccinating the general public in a broader perspective early in the summer. And we should see correspondingly wonderful impacts in the early fall, ”said Dr. Catherine Blish, a specialist in infectious diseases at Stanford.
Blish is still optimistic about the herd’s immunity – even though she, like most of her colleagues, has no idea how long it will take to get there. “The important thing to remember is that we need to be patient,” she said.
Herd immunity occurs when a sufficient number of a population is immune to a virus and is no longer able to spread. Measles is a good example: a sufficient number of people in the United States are vaccinated that the virus only causes problems when cases are brought in from other countries and reach communities that are under-vaccinated, leading to local outbreaks.
Timers are used to track each vaccinated person during a pop-up vaccination clinic at Gilroy Senior Center.
Stephen Lam / The ChronicleIt is unclear exactly how many people will need to be vaccinated to achieve collective immunity with the coronavirus; Dr. Anthony Fauci, the country’s leading infectious disease specialist, estimated 70% to 85%. But it is a moving target, based on how vaccines are protective against new variants and other factors, including vaccine effectiveness in children and how long immunity lasts. Children are unlikely to be eligible for vaccines until the beginning of next year, but studies have found that they are not causing the pandemic.
Regardless of what the final percentage is, and assuming the vaccine supply becomes more reliable, many parts of the United States can come close to collective immunity in six to eight months.
Along the way, counties are expected to see a continuous and noticeable decrease in hospitalizations and deaths. Some experts believe vaccines are already helping, with fewer outbreaks in nursing homes in particular. The effects are likely to become more apparent next month if counties continue to reopen the economy and hospitalizations do not increase again – although there is a risk of a further increase in cases if more infectious variants are established, public health officials warn.
As soon as communities achieve collective immunity, new cases are expected to decline rapidly. If the Bay Area were an island, after vaccinating about 80% to 90% of residents, the pandemic could end in two weeks, said Dr. George Rutherford, an infectious disease specialist at UCSF.
But global ties mean that even after the region or the state, or even the country, reaches levels of herd immunity, the coronavirus will remain a threat – but with less changes in life. If communities can reduce cases to just a handful a day, then they can quickly isolate and contain new infections that are imported and prevent outbreaks.
“How would we live if there were 10 or 20 cases a day or even 100 cases a day in the United States? We would be enjoying life considerably, ”said Dr. John Swartzberg, an infectious disease specialist at UC Berkeley. The United States currently reports well over 50,000 cases per day. “This is what we can achieve with collective immunity.”
Assuming that the herd’s immunity is achievable, there are several variables that can delay it. An unknown is how long immunity lasts after people are vaccinated. Some infectious disease specialists fear that immunity may start to decline in just a few months, which would mean that the first round of people to be vaccinated will need boosters before the final groups receive a single dose. But most experts believe that immunity is likely to last longer, perhaps years.
Variants can complicate things and may even make collective immunity an impossible goal if the virus mutates too fast for vaccines to keep up. But even in this case, vaccines would probably prevent the most serious illness and the coronavirus could end up similar to the flu, in terms of how it affects everyday life and the impact on health systems.
The most worrying variants so far are from South Africa and Brazil, both identified in small numbers in the United States; two cases of the South African variant were found in the bay area. These variants reduce the effectiveness of vaccines and can also prevent natural immunity from previous infections. This may mean that more people need to be vaccinated or need reinforcements for the population to achieve collective immunity.
“Current vaccines will still make a difference. They just can’t necessarily proclaim 95% effectiveness, ”said Shannon Bennett, head of science at the California Academy of Sciences. “But I would take 60% in the blink of an eye.”
The biggest concern with variants is what lies ahead – if those that have already emerged are able to partially escape vaccines, what will happen if future variants escape completely? This reasoning is part of the rush to vaccinate as many people as quickly as possible, because the less the virus can circulate, the less it can turn into something more dangerous.
The launch of the vaccine has been notoriously uneven in the United States. Many county and city leaders said they had staff and other resources to reach almost all those approved for vaccinations by the end of the summer. But these plans are based on supply, which is increasing, but has been hampered by everything from government disorganization to winter storms. It is also unclear what proportion of the population will refuse to get the vaccine, even if it is eligible.
Many public health experts are increasing calls to prioritize the vaccine for communities most affected by the pandemic. Focusing on these neighborhoods is important for two reasons: to protect the people who have already suffered the most and to accelerate the climb towards collective immunity.
“You want your vaccines to interrupt transmission cycles,” said Dr. Kirsten Bibbins-Domingo, vice president of Population Health and Health Equity at UCSF. “The virus has not been hiding. We know where you’ve been. So go out there and vaccinate everyone there. “
“The slow release of the vaccine, the increase in variants and this extremely uneven distribution make me really think that we will not achieve effective herd immunity in the short term, or perhaps never,” she said.
Public health officials said they were aware of the need to vaccinate communities with the highest case rates, and many counties have opened clinics in these neighborhoods. Last week, health officials opened an instant vaccination clinic one day a week in Gilroy, which has the highest infection rate in Santa Clara County.
Gilroy resident 57-year-old Patricia Lugo showed up with her 83-year-old mother on Wednesday so that the two could get vaccinated; Lugo qualifies as his mother’s primary caregiver. Lugo said she kept them extremely isolated to prevent infection, but she was nervous about the vaccine being so new and the side effects. She had made two previous appointments for the photo and canceled.
The arrival of the South African variant in the Bay Area finally convinced her. In addition, she wants to set an example for her four adult children, who have reservations about vaccination. She knows that until everyone is vaccinated, she cannot hug her children and grandchildren. Nor can your community recover.
“I want everyone to do it, so that we are all safe and our lives are back to normal,” said Lugo a few minutes after giving the first chance. “Today I decided to overcome my fear. This is what I need to do. “
Erin Allday is a writer for the San Francisco Chronicle. Email: [email protected] Twitter: @erinallday