COVID-19 Immunity Levels in the US: CDC Report Data

By late 2022, over 95% of the U.S. population had developed some form of immunity to SARS-CoV-2, either through vaccination, infection, or both1 . This high level of immunity has contributed to reduced rates of severe COVID-19 and hospitalizations nationwide1 . However, immunity wanes over time, and vaccination remains a critical tool to sustain protection against emerging variants and severe disease2 .

US Population Immunity Estimates

Population immunity to COVID-19 in the United States has reached very high levels, with estimates exceeding 95% by late 2022 due to widespread vaccination and infection-induced immunity3 1. Seroprevalence studies, which measure the presence of antibodies in blood samples, have been instrumental in estimating these immunity levels1 4. For example, a serosurvey of blood donors found that 96.4% of Americans over age 16 had SARS-CoV-2 antibodies by September 20225 .

The rise in population immunity was driven by both vaccination campaigns and widespread infections during 2021 and 20226 . Adults aged 65 years or older were estimated to have the highest immunity levels, with an overall population immunity mean of 62.0% (credible interval 58.4% to 66.4%) in some analyses7 . Children also showed high seroprevalence, with over 90% having antibodies by the end of 2023, although younger children remain more likely to lack protective antibodies4 .

Despite these high immunity levels, antibody concentrations decline over months, and immunity from prior infection or vaccination does not fully prevent reinfection or severe outcomes1 8. Booster vaccinations are recommended to sustain immunity, especially for high-risk groups such as older adults and immunocompromised individuals9 10. However, booster uptake remains suboptimal, with only about 17% of the population having received the updated bivalent booster as of late 202211 12.

• Widespread vaccination and natural infection contributing to antibody prevalence1 6.
• Higher immunity levels in older adults compared to younger populations7 .
• Waning antibody levels necessitating booster doses to maintain protection13 14.
• Low booster uptake despite recommendations11 12.
• Use of seroprevalence studies to monitor immunity trends over time1 4.

💡 Did You Know? Antibodies to SARS-CoV-2 were present in the blood of 96.4% of Americans over age 16 by September 2022, indicating widespread immunity5 .

Types of COVID-19 Immunity

COVID-19 immunity in the U.S. population arises from three main sources: vaccination, natural infection, or a combination of both, known as hybrid immunity6 1. Understanding these sources is essential to assess the level of protection against infection and severe disease.

• Infection-induced immunity is more common among unvaccinated individuals who have recovered from COVID-191 .
• Vaccine-induced immunity predominates among vaccinated persons without prior infection1 .
• Hybrid immunity, resulting from both vaccination and prior infection, provides the strongest and most durable protection against reinfection and severe outcomes15 1.

Vaccination reduces the risk of SARS-CoV-2 infection and reinfection compared to unvaccinated status, even in the context of prior infection16 . Hybrid immunity offers superior protection, combining the benefits of vaccine-elicited and natural immune responses15 1.

Antibody presence, measured through seroprevalence studies, indicates some level of protection but does not guarantee complete immunity. Protection wanes over time as antibody levels decline, although memory immune responses may persist longer and contribute to defense against severe disease13 1418.

Vaccination is recommended over natural infection due to its safer and more predictable immune response, reducing risks associated with COVID-19 illness2 1.

• Infection-induced immunity: common in unvaccinated, from prior infection1 .
• Vaccine-induced immunity: from vaccination without prior infection1 .
• Hybrid immunity: strongest protection from both vaccination and infection15 1.
• Antibodies indicate protection but do not fully prevent reinfection1 8.
• Immunity wanes; boosters help sustain protection13 14.
• Vaccination is safer and more reliable than natural infection2 1.

“Vaccination reduces the risk of SARS-CoV-2 infection and reinfection compared to unvaccinated status.”

— CDC COVID-19 Vaccine Effectiveness Update16

Future COVID-19 Trends and Data

Ongoing surveillance and vaccine effectiveness studies inform our understanding of COVID-19 immunity and guide public health recommendations. Despite the high levels of immunity, COVID-19 continues to pose a serious health threat, especially to older adults and immunocompromised individuals17 .

The Centers for Disease Control and Prevention (CDC) and the Advisory Committee on Immunization Practices (ACIP) recommend updated COVID-19 vaccines, including bivalent boosters targeting currently circulating variants, for all eligible persons aged 6 months and older9 1018. Booster doses provide additional protection against COVID-19-associated emergency department visits and hospitalizations, with vaccine effectiveness estimates ranging from 33% to 46% in recent studies19 .

However, booster uptake remains low, with only about 23% of adults following the most recent seasonal booster recommendation20 . This low uptake may impact the overall population immunity and the severity of future COVID-19 waves.

Scenario modeling for the 2025–2026 respiratory disease season predicts that COVID-19 hospitalization rates may be similar to or higher than the previous season, especially if a new variant with moderate immune escape emerges21 . Factors influencing future trends include:

• Emergence of new SARS-CoV-2 variants with immune escape capabilities21 .
• Seasonal fluctuations in COVID-19 activity, including summer and winter waves21 .
• Vaccination uptake and effectiveness, particularly among high-risk groups21 .
• Waning immunity and the need for timely booster doses13 14.

Vaccination remains the safest and most effective strategy to reduce COVID-19 morbidity and mortality. Co-administration of COVID-19 vaccines with influenza vaccines is recommended to improve vaccination coverage and maintain immunity during the respiratory virus season22 2.

• Receive updated COVID-19 vaccines annually, especially if aged 65 or older or immunocompromised9 10.
• Discuss vaccination benefits with healthcare providers, particularly for children aged 6 months to 17 years18 23.
• Monitor and respond to emerging variants through updated vaccine formulations24 .
• Promote co-administration of COVID-19 and influenza vaccines to enhance protection22 2.
• Increase public awareness to improve booster uptake11 20.