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Vaccine

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Q&A #64 with Dr. Rhonda Patrick (11/2/24)

Posted on November 19th 2024 (6 months)

Dr. Rhonda Patrick discusses silicone safety, grounding, pentadecanoic acid, and the potential benefits of olive leaf extract and peptides.

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Q&A #42 with Dr. Rhonda Patrick (12/3/22)

Posted on December 3rd 2022 (over 2 years)

Dr. Rhonda Patrick answers audience questions on various health, nutrition, and science topics in this Q&A session.

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Q&A #33 with Dr. Rhonda Patrick (3/5/2022)

Posted on March 5th 2022 (about 3 years)

Dr. Rhonda Patrick answers audience questions on various health, nutrition, and science topics in this Q&A session.

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News & Publications

  • mRNA vaccines provide long-lasting immunity and protection from SARS-CoV-2 variants. www.bloomberg.com
    Immune System Vaccine COVID-19

    SARS-CoV-2 mRNA vaccines (e.g., Moderna and Pfizer-N-BioTech) are effective in preventing infection and have even greater efficacy in preventing severe COVID-19 illness and hospitalization. However, many people in the United States received their vaccine early in 2021, more than six months before the time of this writing. Whether the protection afforded by vaccination lasts as time passes and more SARS-CoV-2 variants emerge is unclear. Findings of a report published in August provide insights into long-term immunity following vaccination or SARS-CoV-2 infection, concerns about emerging variants, and implications for vaccination boosters.

    During infection with a virus, the innate immune system immediately produces inflammation to fight the infection. Within days or weeks, the adaptive immune system produces antibodies that are specific to the virus. These antibodies bind to a small piece of the viral particle, called an antigen. White blood cells such as macrophages and neutrophils participate in the innate response, while B and T cells facilitate the adaptive response. Plasma B cells are responsible for producing antibodies; however, these cells steadily decrease in number over time. Memory B cells store the genetic information needed to produce virus-specific antibodies upon reinfection. Memory T cells are also responsible for “remembering” viruses in this way. Memory CD4+ T cells rapidly respond to reinfection to support inflammation and antibody production. Memory CD8+ T cells, also called cytotoxic T cells, bind to virus-infected host cells and order them to undergo apoptosis (i.e., programmed cell death).

    The authors of the report analyzed a set of 342 blood samples collected from 61 participants at one, three, and six months following vaccination. This group of participants included SARS-CoV-2 naive individuals (i.e., those who were never infected with the virus) and SARS-CoV-2 recovered individuals. The investigators measured the concentration of circulating antibodies that bind to the SARS-CoV-2 receptor binding domain protein and spike protein. They also measured the concentration of memory B cells and T cells and characterized these cells’ response when challenged with SARS-CoV-2 antigens.

    The concentration of serum antibodies declined over time, but was still detectable at six months post-vaccination. mRNA vaccination produced memory B cells that respond to the receptor binding domain protein of the Alpha, Beta, and Delta variants, called cross-binding memory. These memory B cells had significantly more hypermutation, the process by which B cells rearrange their DNA in order to produce antibodies to new antigens, and increased in concentration between three and six months post-vaccination. Cross-binding B cells were more common in SARS-CoV-2 recovered patients than naive patients. mRNA vaccination also increased memory CD4+ and CD8+ T cells.

    The immune response to mRNA vaccination and infection with the SARS-CoV-2 virus evolves over time, which may have implications for the future use of booster vaccines. These results should be considered with caution as this research has yet to be peer-reviewed.

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  • COVID-19 vaccines are less effective against the delta variant, especially the Pfizer-BioNTech vaccine. www.axios.com
    Vaccine COVID-19

    As the COVID-19 pandemic continues into its second year, a number of variants have emerged, such as the delta variant, which is a highly contagious SARS-CoV-2 variant first identified in India in December 2020. The increase in transmissibility - the ability of a disease to be passed from one individual to another - is due to mutations of the viral spike protein, which allows entry into human cells. Findings of a report released this week show that vaccines that were effective against the original SARS-CoV-2 strain are less effective against the delta variant.

    Viruses are small particles containing genetic material (RNA in the case of SARS-CoV-2) and a lipid capsule with protein structures on the surface. They do not contain the cellular machinery to create new viruses and depend on host cells for replication. Messenger RNA (mRNA) vaccines, such as the Pfizer-BioNTech and Moderna vaccines, work by delivering modified viral RNA encapsulated in a lipid membrane to human cells. These lipid droplets fuse with the lipid membranes of human cells in the respiratory tract and elsewhere and deliver mRNA to the inside of the cell. Once inside the cell, the vaccine mRNA directs the cell to produce more of the modified viral protein. This tricks the immune system into thinking these cells are infected and the body mounts an immune response that ultimately results in the production of antibodies that bind to the SARS-CoV-2 spike protein, preventing subsequent infection.

    Reports published before the emergence of the delta variant demonstrate an efficacy of 95 percent for the Pfizer-BioNTech vaccine and 93 percent for the Moderna vaccine against the original Wuhan Hu-1 strain. Because the delta variant has a modified spike protein, it is unclear if vaccines designed for the original SARS-CoV-2 spike protein will be effective against current and future variants.

    The authors analyzed data from patients of the Mayo Clinical Health System in Minnesota, Wisconsin, Arizona, Florida, and Iowa starting in January 2021, when the original SARS-CoV-2 strain was most prevalent, and ending in July 2021, when the delta variant was most prevalent. The study included more than 25,000 vaccinated participants and 25,000 unvaccinated participants matched for age, sex, race, ethnicity, state of residence, and history of prior SARS-CoV-2 testing.

    The delta variant prevalence in Minnesota increased from less than one percent in May 2021 to over 70 percent in July 2021; whereas the original strain prevalence decreased from 85 percent to 13 over the same period. The researchers found that the Moderna vaccine was between 81 and 91 percent effective and the Pfizer-BioNTech vaccine was between 69 and 81 percent effective against infection with the original SARS-CoV-2 virus prior to May 2021. These vaccines were also highly effective in preventing hospitalization from infection with the original virus with the Moderna vaccine showing 81 to 97 percent efficacy and the Pfizer-BioNTech vaccine showing 73 to 93 percent efficacy. By July, the total effectiveness in preventing infection decreased to 76 percent for the Moderna vaccine and 42 percent for the Pfizer-BioNTech vaccine, indicating a loss of efficacy over time as variants became more common.

    Next, the authors compared vaccine effectiveness across multiple states over the entire study period. In most states, the Moderna vaccine was twice as effective in preventing breakthrough infections than the Pfizer-BioNTech vaccine. This difference in effectiveness against breakthrough infections between the vaccines was highest in July, when the delta variant was most prevalent. This was especially true in Florida, where the risk of breakthrough infection was 60 percent lower after vaccination with the Moderna vaccine compared to the Pfizer-BioNTech vaccine. Across all dates, the Moderna vaccine was twice as effective in preventing COVID-19 associated hospitalization compared to the Pfizer-BioNTech vaccine.

    While both vaccines demonstrate effectiveness in preventing infection and hospitalization, their effectiveness has declined over time as the prevalence of SARS-CoV-2 variants increased. The authors suggested additional studies in large and diverse populations are needed to guide public health policy. This manuscript has yet to be peer-reviewed.

    Previous infection with the original strain of the SARS-CoV-2 along with vaccination creates what is known as “hybrid immunity.” People who have hybrid immunity have a broader and more robust antibody response, as observed in this trial, which is covered in this edition of the Science Digest.

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  • Previous infection with SARS-CoV-2 plus vaccination protects against variants. www.nature.com
    Vaccine COVID-19

    The delta variant of SARS-CoV-2, the virus that causes COVID-19, is one of multiple variants to exhibit increased resistance to antibodies as well as higher transmissibility. It is unclear if vaccination or prior infection with the original Wuhan Hu-1 strain is effective against these emerging variants. But now, a new report suggests individuals who have recovered from infection with the original SARS-CoV-2 strain are protected from variants such as delta, especially following vaccination.

    A virus strain is considered the “parent” form of a virus. For example, SARS-CoV-1 and SARS-CoV-2 are strains of the broader SARS-CoV line of viruses. To be considered a variant, a virus must have sufficient mutations to change a portion of its genetic code. In the case of the delta variant, increased transmissibility is the result of genetic changes to the receptor binding domain, a portion of the viral spike protein. This protein enables viruses to enter cells and is the main target of SARS-CoV-2 vaccines. Its genetic change in the delta variant has scientists concerned that individuals who have recovered from the original virus or an early variant may not be protected against later variants with altered spike proteins.

    During infection with a virus, the innate immune system immediately produces inflammation to fight the infection. Within days or weeks, the adaptive immune system produces antibodies that are specific to the virus. These antibodies bind to a small piece of the viral particle, called an antigen. Plasma B cells are the white blood cells responsible for producing antibodies; however, these cells steadily decrease in number over time and do not protect against reinfection with the same virus. Memory B cells store the genetic information needed to produce virus-specific antibodies upon reinfection.

    The authors of the novel report recruited 63 participants between the ages of 26 and 73 years old who were convalescent, meaning they had recovered from SARS-CoV-2 infection. Some participants had received a vaccine (only mRNA vaccines were included) and others had not. The researchers collected blood samples from their participants at about six weeks, six months, and one year following infection in order to characterize their immune responses specifically to the receptor binding domain of the SARS-CoV-2 spike protein. Immunity measures included specificity (the number of antigens to which an antibody will bind), reactivity (the strength to which an antibody binds its antigen), and neutralizing activity (the antibodies' ability to block infection).

    Their analysis revealed that convalescent participants who had not been vaccinated maintained their plasma antibody levels 12 months following infection, providing protection from reinfection. Notably, convalescent participants who had received an mRNA vaccine had 30 times more antibodies and 50 times greater neutralizing activity against the original SARS-CoV-2 strain 12 months following infection than unvaccinated convalescent participants. Neutralizing activity against the alpha, beta, iota, and gamma variants was also ten times greater at 12 months compared to vaccinated individuals who have never had the virus. This means the immune system will react strongly if a vaccinated convalescent individual catches one of the viral variants.

    Antibody-producing B cells evolved over time in both vaccinated and unvaccinated convalescent participants; however, receiving an mRNA vaccine increased receptor binding domain antibodies eightfold. Without vaccination, convalescent participants lost a significant portion of antibodies that were specific for the receptor binding domain of the spike protein at six months post-infection, putting them at greater risk for reinfection. The authors showed that memory B cells continually mutate their antibody structures to increase reactivity and specificity over time, providing stronger immunity against a wider array of strains.

    The authors concluded that immunity in convalescent individuals is long lasting. Vaccination provides additional protection against SARS-CoV-2 variants in convalescent individuals. However, an article covered in this edition of the Science Digest suggests current mRNA vaccines may be less effective against the delta variant in vaccinated people who have never had a SARS-CoV-2 infection.

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