Superior safety with ‘mix-and-match’ COVID-19 booster technique

The coronavirus illness 2019 (COVID-19) pandemic was attributable to the sudden world outbreak of the extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Since SARS-CoV-2 emerged on the finish of 2019, scientists have labored relentlessly to develop a number of vaccines to scale back the transmission of SARS-CoV-2 and shield people from extreme COVID-19.

Just lately, a speedy decline within the degree of antibodies elicited by vaccination with messenger ribonucleic acid (mRNA) vaccines has been noticed. In a brand new Jama Network Open research, researchers talk about the sturdiness and immunogenicity of homologous and heterologous booster regimens with the Johnson & Johnson Ad26.COV2.S and Pfizer-BioNTech BNT162b2 vaccines.

Study: Durability of Heterologous and Homologous COVID-19 Vaccine Boosts. Image Credit: PhotobyTawat /

Examine: Durability of Heterologous and Homologous COVID-19 Vaccine Boosts. Picture Credit score: PhotobyTawat /


Excellent short-term immunogenicity and protecting efficacy have been related to mRNA COVID-19 vaccines. Nonetheless, between three to 6 months after major vaccination, neutralizing antibody (nAb) responses decline. The same decline in nAb ranges has been noticed after the third and fourth mRNA booster doses that have been provided to offer safety in opposition to the extremely mutated Omicron variant.

As in comparison with mRNA vaccines, decrease preliminary nAb titers are induced by the Johnson & Johnson adenovirus vector-based COVID-19 Ad26.COV2.S vaccine. Nonetheless, these responses have been maintained for at the very least eight months.

Earlier analysis has proven that CD8+ T-cell responses could contribute to safety in opposition to extreme illness and are extra sturdy than serum nAb titers. T-cell responses are considerably crossreactive in opposition to the Omicron variant, regardless of the flexibility of this variant to evade nAbs elicited by vaccination.

Optimum boosting methods are the topic of lively analysis, the outcomes of which shall be instrumental for long-term pandemic management.

Concerning the research

The first goal of this research was to research the sturdiness and immunogenicity of homologous and heterologous vaccine booster methods.

This research was carried out at a medical website in Boston, Massachusetts. Taken collectively, 68 research individuals who acquired two doses of the BNT162b2 vaccine and have been boosted with both the BNT162b2 or Ad26.COV2.S vaccines at the very least six months after finishing their major vaccination have been included within the present research.

People with a historical past of SARS-CoV-2 an infection, in addition to receipt of different COVID-19 vaccines or immunosuppressive drugs, have been excluded from the research. Moreover, people weren’t allowed to take part if that they had a confirmed breakthrough SARS-CoV-2 an infection or optimistic nucleocapsid serology as detected by an electrochemiluminescence assay (ECLA).

Examine individuals have been enrolled between August 12, 2021, and October 25, 2021, with an extra 4 months of follow-up after the research interval ended. Information evaluation to judge humoral and mobile immune responses was carried out between November 2021 and February 2022.

Examine findings

Homologous boosting generated a speedy enhance of Omicron nAbs, which peaked within the second week and subsequently declined by virtually seven-fold by the 16th week. Comparatively, heterologous-boosted nAbs peaked within the fourth week and declined by about two-fold by the 16th week. These outcomes are in step with different findings describing the sturdiness of immune responses following preliminary mRNA vaccination with a booster dose of the Ad26.COV2.S vaccine.

The heterologous booster dose was additionally related to greater Omicron-specific CD8+ T-cell responses. This response stays extremely cross-reactive in opposition to the Omicron variant, regardless of the flexibility of this variant to evade nAbs elicited by vaccination.

In South Africa, BNT162b2 and Ad26.COV2.S vaccines offered 70% and 85% efficacy, respectively, in opposition to hospitalization with the Omicron variant within the absence of nAbs. This remark suggests the essential function of different immune responses in rendering safety in opposition to extreme COVID-19.


A key limitation of the present research pertains to its small measurement at a single website in Boston. Moreover, there was a scarcity of randomization, and females have been over-represented.

Thus, future analysis utilizing bigger and extra consultant pattern sizes is required. Moreover, follow-up instances past 16 weeks are required to evaluate long-term sturdiness.


Taken collectively, heterologous and homologous booster vaccination generated Omicron-specific antibody and T-cell responses in mRNA-vaccinated people. Notably, heterologous vaccination elicited greater nAb and CD8+ T-cell responses. These observations recommend the advantages of heterologous vaccine regimens.

Journal reference:



Leave a Reply