Covid will soon be endemic, thank goodness

Australia, China and New Zealand have pursued “zero Covid” policies aimed at elimination (reduction of incidence in a region) or even eradication (global elimination). This goal is unrealistic. Smallpox is the only human disease that has ever been eradicated. The smallpox virus had four properties that made it eradicated: the absence of an animal reservoir, clear and distinctive signs and symptoms, a short period of infectivity, and both natural immunity for life afterwards. survival and a very effective vaccine.

SARS-CoV-2, on the other hand, is unlikely to be eradicated. It has animal reservoirs, a high level of transmissibility (especially the Delta variant), and symptoms that overlap with other respiratory illnesses. It also has a prolonged period of infectivity, caused by its propensity to spread from asymptomatic or presymptomatic carriers.

This is why reducing the disease from epidemic to endemic is the best case, one that will allow a full return to normal. Many ineradicable infections are controlled with vaccination and treatment. Measles, a highly transmissible respiratory virus, created high levels of immunity in adults who were exposed as children. But until a vaccine was developed in 1963, some non-immune adults died every year. Whooping cough (whooping cough) is caused by a highly contagious bacteria (with syndromes that overlap with some respiratory viruses), but it is controlled in the United States with childhood vaccinations, antibiotics, and other treatments. (However, parental reluctance to get vaccines in the United States has led to outbreaks of pertussis and measles over the past decade.)

Authorities have tried a wide range of measures to control SARS-CoV-2: masks, social distancing, lockdowns, travel restrictions, ventilation, testing, contact tracing. These have had varying levels of success but ultimately proved insufficient to control the virus sustainably. This will require widespread immunity. Fortunately, safe and effective vaccines have been developed for SARS-CoV-2 in record time. These vaccines are the key to turning Covid-19 into an endemic but controlled communicable disease.

Control means reduction of serious illness, not asymptomatic or mild cases. Since vaccines are remarkably effective in preventing serious illnesses from Covid-19 – which has made SARS-CoV-2 a global threat – they can serve as a vector of control.

Antibodies generated by vaccines will naturally decrease, but vaccines trigger the creation of B cells which are relegated to our memory banks, and these memory B cells produce high levels of neutralizing antibodies if they see the virus again, even under a variant form. Memory B cells have a long lifespan. A 2008 Nature study found that survivors of the 1918 influenza pandemic were able to produce antibodies when exposed to the same strain of influenza nine decades later. The T lymphocytes (also stored in cellular memory) generated by the vaccines protect us from serious diseases and are not disturbed by the variants.

What would the endemic Covid-19 look like? If we can stop the virus from circulating and reduce its ability to cause serious disease with widespread vaccination, the world can get back to normal. Outbreaks of serious illness will occur among populations who do not wish to be vaccinated, as we see with measles and pertussis, but warrants can help increase vaccination rates.

As the circulation of the virus decreases with increasing immunity, Covid-19 will follow the path of other respiratory viruses over which we have control. We will test those who arrive at the hospital for a variety of infections – including influenza, Covid-19, respiratory syncytial virus (mainly in children) and bacterial pathogens – and tailor treatments to the infectious agent . Moderate respiratory symptoms of Covid-19 on an outpatient basis can be treated with monoclonal antibodies or ambulatory antivirals (in development), and mild symptoms (like other common colds) will not require treatment.

The disease burden a country is willing to accept will depend on its priorities: Denmark dropped all restrictions on a 74% vaccination rate and low cases on September 10, and Norway dropped them on September 25. at a vaccination rate of 67%. Many states in the United States suffered an excessive hospital burden during the Delta Wave, although California keeps restrictions in place despite a low hospitalization rate and high vaccination rates. We will have to accept that the disease that has not been eradicated is endemic. A low burden of disease should ease the transition.

Although SARS-CoV-2 has proven to be unpredictable, no virus in history has ever continued to progress to higher pathogenicity. As we have learned from HIV, mutations usually cost viral fitness or weaken the virus. No vaccine-preventable or immunity-inducing infection has ever raged as a pandemic indefinitely. An endemic virus does not require continuous isolation or other restrictions; defaming SARS-CoV-2 by stripping it of its ability to cause severe disease through immunity will relegate it to the fate of the other four circulating cold-causing coronaviruses. The key to this normalcy is immunity. With a highly transmissible variant that increases immunity in the unvaccinated and strengthens it in the vaccinated, Covid-19 will inevitably make the transition from epidemic to endemic.

Dr Gandhi is an infectious disease specialist and professor of medicine at the University of California, San Francisco.