Pharmaceutical giant Johnson & Johnson's experimental COVID-19 vaccine has produced a strong immune response against the novel coronavirus in an early-to-mid stage clinical trial, as per the data published on September 25.
"The data demonstrate that a single dose of COVID-19 vaccine, Ad26.COV2.S, induced a strong neutralising antibody response in nearly all participants aged 18 years and older and was generally well-tolerated," J&J said, adding that the immune responses were similar across the age groups studied, including older adults.
Unlike the three vaccines developed by Moderna, Pfizer and BioNTech, and AstraZeneca and the University of Oxford, that require a re-visit and second shot three to four weeks after the first one to trigger a protective immune response, J&J will be initially testing a single dose.
A single shot, versus a rival two-dose approach being tested by Moderna Inc and Pfizer Inc, could simplify the distribution of the vaccine. The trial in close to 1,000 healthy adults, which is backed by the US government, began after the J&J vaccine was found in July to offer strong protection in a single dose to monkeys.
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Frequently Asked Questions
A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.
There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.
Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.
Based on the current results, J&J on September 23 kicked off a final 60,000-person trial, which could pave the way for an application for regulatory approval. The company said it expects results of the Phase 3 trial by the end of the year or early next year.
"The trial will include those both with and without comorbidities associated with an increased risk for progression to severe COVID-19, and will aim to enrol participants in Argentina, Brazil, Chile, Colombia, Mexico, Peru, South Africa and the United States," Johnson & Johnson said in a statement.
The results, released on the medical website medRxiv, have not been peer-reviewed. Researchers, including those from J&J's unit Janssen Pharmaceuticals, said 98 percent of participants with data available for the interim analysis had neutralizing antibodies, which defend cells from pathogens, 29 days after vaccination.
However, immune response results were available from only a small number of people - 15 participants - over 65 years old, limiting the interpretation.
In participants older than 65, the rate of adverse reactions such as fatigue and muscle aches was 36 percent, much lower than the 64 percent seen in younger participants, the results showed, suggesting the immune response in older people may not be as strong.
The researchers said more details on safety and effectiveness will follow when the study is completed.
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