Innate immunity vs vaccine-induced immunity

In a recent study posted on SSRN*Preprint server, investigator against previous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and/or reinfection by coronavirus disease 2019 (COVID-19) vaccine (hybrid immunity) Conferred immune protection was assessed.

study: Risk of COVID-19 after natural infection or vaccination. Image credit: wanwei/Shutterstock.com

*Important Notices: SSRN We publish a non-peer-reviewed, preliminary scientific report and should not be taken as conclusive, to guide clinical practice/health-related actions, or to be treated as established information.

Background

With the continued increase in vaccination for coronavirus disease 2019 (COVID-19) and SARS-CoV-2 infection, the degree of humoral protection conferred by previous SARS-CoV-2 Further studies are needed to evaluate comparatively and in combination with induced immunity. .

The authors searched the PubMed Central database between 1 March 2020 and 1 June 2022 for randomized controlled trials (RCTs) and other studies assessing protection against SARS-CoV-2 reinfection. I looked for research.

12 studies evaluating COVID-19 vaccines from over 100 initially eligible records Effectiveness, and 10 records of humoral immunity were reviewed. Most studies were observational, single-center type, or reported findings from previously conducted RCTs.

Additionally, these studies utilized a variety of techniques, including self-recording data and anti-SARS-CoV-2 antibody titers, to assess baseline SARS-CoV-2 exposure. Phase 3 efficacy trials reported that previous infection and/or vaccine conferred immunity. However, the degree of immunity varied. Follow-up periods and variants of concern (VOCs) varied.

About research

In the current post-hoc cross-protocol study, researchers comprehensively evaluated the immune protection conferred by previous SARS-CoV-2 infection alone or in combination with the COVID-19 vaccine.

Individual-level data are from a United States (US) Government-funded harmonized study evaluating Janssen’s Ad26.COV2.S, Moderna’s mRNA-1273, Novovax’s NVX-CoV2373, and AstraZeneca’s AZD1222 vaccines. Obtained from a randomized controlled trial (RCT) of a COVID-19 vaccine.

Study participants (n=134,935) from four trials were divided into four groups as follows: history/placebo (n=3,367); no history/COVID-19 vaccine (n=71,622); and previous infection/COVID-19 vaccine (4,272) groups.

The main findings were reverse transcription-polymerase chain reaction (RT-PCR)-confirmed SARS-CoV-2 infection more than 2.0 weeks after the first Janssen vaccination, more than 2.0 weeks after the second Moderna vaccination, occurred more than 15.0 days after the second AstraZeneca vaccination. , and more than 1.0 weeks after his second Novavax vaccination.

Crude adjusted measures of COVID-19 vaccine efficacy were calculated, including the adjusted risk ratio (aRR).

Data were adjusted for race, sex, age, ethnicity, comorbidities, and SARS-CoV-2 exposure risk at baseline. All trials used a SARS-CoV-2 nucleocapsid (N) protein-based immunoassay to identify individuals with a history of COVID-19.

Individuals were recruited between 27 July 2020 (Moderna) and 27 December 2020 (Novavax) and were followed until the end of the blind stage or the start of the crossover (Moderna: 31 March 2021; Novavax: 1 June 2021; Janssen: 17 July 2021; AstraZeneca: 30 July 2021). The team excluded individuals with missing RT-PCR and serological data.

result

During follow-up, the incidence of symptomatic SARS-CoV-2 infection was 1,600 for Janssen vaccines, 810 for Moderna vaccines, 326 for AstraZeneca vaccines, and 89 for Novavax vaccines. was a person

Individuals in the previous infection/placebo group showed a 93.0% reduction in risk of SARS-CoV-2 infection compared to the previous infection/placebo group (aRR 0.07). In contrast, Janssen vaccine recipients in the previous infection/placebo group had a lower risk of COVID-19 than individuals in the previous infection/Janssen vaccine group (aRR 0.13).

Among single-dose Janssen vaccinees, hybrid immunization provided better immune protection compared with vaccination alone (adjusted risk ratio 0.03). Other vaccine trials had too few SARS-CoV-2 infections to infer data comparing hybrid immune protection to that conferred by vaccination.

Prior infection and/or vaccination conferred near-complete immunity to COVID-19 severity. Prior infection, hybrid immunoprotection, and two-dose vaccination significantly protected against severe and symptomatic Delta VOC infection. Therefore, COVID-19 vaccination remains the safest strategy for immune protection as a surrogate for previous infection.

Uninfected individuals who received the COVID-19 vaccine were shown to have a 54% to 92% lower relative risk of SARS-CoV-2 infection than individuals in the previously uninfected/placebo group. A sensitivity analysis performed by excluding individuals who were seronegative at study entry but were PCR positive yielded similar results.

Additionally, less than 0.1% of the 71,835 vaccinees and none of the 7,639 who had previous infection or hybrid immunity had experienced severe SARS-CoV-2 infection. In contrast, 0.60% of the 52,045 women in the naive/placebo group developed severe SARS-CoV-2 infection.

Conclusion

Overall, the results of this study showed that previous SARS-CoV-2 infection in placebo recipients reduced COVID-19 risk by 93%. Hybrid immunity appeared to be highly protective, equivalent to two doses of the COVID-19 vaccine.

Janssen’s single-dose clinical trial found that prior infection alone or in combination with COVID-19 vaccination provided better immune protection than single vaccination in SARS-CoV-2-naïve individuals .

Asymptomatic or mild SARS-CoV-2 infection in the first wave of COVID-19 is associated with severe COVID-19 over 3 to 6 months during periods when the SARS-CoV-2 Delta VOC predominates. and significantly prevented reinfection.

However, immune protection is likely to differ based on the predominant VOC, and previous infection without COVID-19 vaccination may not confer sufficient immunity against all SARS-CoV-2 VOCs. I have.

*Important Notices: SSRN We publish a non-peer-reviewed, preliminary scientific report and should not be taken as conclusive, to guide clinical practice/health-related actions, or to be treated as established information.