• COVID outbreak in party town shows how the pandemic could end | The Seattle Times

    He and colleagues studied the immune responses of 35 vaccinated people tested for COVID in the Provincetown outbreak.

    Those who got a breakthrough infection had a dramatic increase in levels of virus-blocking antibodies and virus-killing T cells, including 34-fold higher neutralizing antibody levels against the delta variant, compared with those who weren’t infected.

    An infection five-to-six months after vaccination jolted the body’s immune memory into gear to generate potent, delta-specific antibodies and T cells that helped clear the virus before it caused severe illness or had the chance to spread.

    “We think that this is likely the reason why vaccinated people who get breakthrough infections generally have a mild course of disease in the vast majority of cases, because they have a rapid onset of very potent antibody and T cell responses that likely control the virus,” Barouch said over Zoom. “It is likely that those individuals will have high levels of immunity for a prolonged period of time.”

    He’s planning to follow the people who had a breakthrough infection to understand the duration of their immunity.

    “Do those responses maintain themselves at that high level, or do they then go down over time?” Barouch asked. “That’s a very important question to address.”


    It’s expected that the severity of disease and the propensity for onward transmission will decline as each exposure trains the immune system to recognize and respond to the coronavirus faster, including current and future variants.

    Over time, SARS-CoV-2 will likely cease being a public health menace and resemble something akin to the coronaviruses that cause the common cold, said University of Auckland’s Petousis-Harris.


    “An expectation for many diseases is that periodic low-grade exposure, resulting in either no infection or asymptomatic infection, boosts immunity and memory,” said Shane Crotty, a professor in the Center for Infectious Disease and Vaccine Research at San Diego’s La Jolla Institute for Immunology. “If that’s observed for #SARS-CoV-2 with asymptomatic breakthrough infections, that will be clear evidence of the same phenomenon.”