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Sputnik V COVID-19 vaccine: How much do we know about its side effects?

Sputnik V, developed by the Gamaleya National Center of Epidemiology and Microbiology in Russia, was the first COVID-19 vaccine to be authorized. This Snapshot feature discusses some of the common side effects reported in clinical trials, as well as controversies around potential safety concerns of the vaccine.

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A healthcare worker prepares to administer Russian Sputnik V COVID-19 vaccine. Ezra Acayan/Getty

The Gamaleya National Center of Epidemiology and Microbiology in Moscow, Russia, developed a COVID-19 vaccine called Gam-COVID-Vac, more commonly known as Sputnik V. It is the first COVID-19 vaccine in the world to be authorized for use against the SARS-CoV-2 virus.

Along with Russia, 64 countries have approved the vaccine. These countries include Argentina, Iran, and India. The vaccine is currently being reviewed in the European Union by the European Medicines Agency.

Sputnik V is a two-part adenovirus viral vector vaccine with an efficacy rate of 91.6%.

Adenoviruses are a type of virus associated with the common cold and other illnesses. They serve as the delivery vehicle for the DNA instructions to produce the spike protein of the SARS-CoV-2 virus in the body. This then triggers the production of antibodies against this spike protein, preparing the immune system for a potential infection.

Each of the two doses uses a different type of adenovirus: first dose with type-26 (Ad26), then a booster dose with type-5 (Ad5). The purpose of using two different types is to lower the possibility of the body developing antibodies against the adenovirus after the first dose, which could make the second dose ineffective.

The Johnson & Johnson COVID-19 vaccine, also an adenovirus-based vaccine, uses Ad26 for its single dose.

An interim analysis of phase 3 clinical trial data, published in The Lancet in February 2021, reports on the efficacy and safety of the vaccine. Based on the data, the most common side effects were:

These side effects are similar to those of the Pfizer, Moderna, and Johnson & Johnson COVID-19 vaccines, as noted by the Centers for Disease Control and Prevention (CDC).

Authors of the paper state that 45 out of 16,427 participants who received the vaccine reported serious adverse events, including deep vein thrombosis, hemorrhagic stroke, and hypertension. However, according to the paper, the independent data monitoring committee has confirmed that none of these were considered related to the vaccine.

Despite these data, there is still a significant controversy surrounding the vaccine. Experts have received the results with skepticism due to Russia’s strategy of early approval in August 2020, along with the lack of published raw data or protocol.

Adenoviruses, in their natural state, are able to replicate in the body and lead to illnesses, such as the common cold. When used in vaccines, adenoviruses are altered to remove their ability to replicate. For the Sputnik V vaccine, it was noted that the E1 gene was removed from the vaccine in order to prevent replication.

However, Brazil recently rejected the use of Sputnik V, citing concerns around replication. According to Anvisa, the Brazilian Health Regulatory Agency, quality control documents revealed that batches of the vaccine displayed “less than 100 replication-competent particles per dose,” suggesting that the adenovirus does have a small chance of replication.

Shortly after, the Gamaleya National Center released a press statement denying Anvisa’s allegations, referring to Brazil’s decisions as being “of a political nature and [having] nothing to do with the regulator’s access to information or science.”

It stated that only non-replicating adenoviruses are incorporated in the vaccine, and pointed to other strict aspects of quality control.

Scientists have displayed mixed responses, with some criticizing Russia’s lack of transparency and others questioning Anvisa’s interpretation of the data. In the case that the adenovirus is able to replicate, the likely side effects are a mild common cold for most people. For people with weakened immune systems, the risks may be greater.

After CanSino released phase 1 clinical trial data on Convidecia, another Ad5-based COVID-19 vaccine, researchers raised concerns regarding the potential dangers of incorporating Ad5 into COVID-19 vaccines.

According to a 2008 study observing the efficacy of an HIV-1 vaccine, the adenovirus Ad5 found within vaccines may be associated with an increased risk of HIV acquisition.

While further research is needed to validate this claim, the researchers advise precaution against using Ad5-based COVID-19 vaccines, particularly in areas of the world with a high number of HIV and AIDS cases.

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