Johnson & Johnson’s Janssen vaccine: efficacy and side effects

Johnson & Johnson’s Janssen vaccine: efficacy and side effects
Johnson & Johnson’s Janssen vaccine: efficacy and side effects

Authorized last March 12 byAifa and used in the vaccination campaign starting from April 22, the vaccine Janssen di Johnson & Johnson was the fourth available in Italy for the prevention of Covid-19 disease and it is to date the only one to have the advantage of being administered in a single dose.

Like AstraZeneca, Johnson & Johnson’s is also a viral vector vaccine, or consisting of another virus, belonging to the family of adenovirus, modified to contain the gene responsible for the formation of the Spike protein present in SARS-CoV-2. The technology used is similar: the adenovirus in fact transmits the SARS-CoV-2 gene into the cells of vaccinated people to ensure that the immune system recognizes the Spike protein as foreign, thus producing antibodies and activating T lymphocytes (white blood cells) to target it.

As happened with AstraZeneca, so is the vaccine Janssen was at the center of a tight succession of news: in fact, under scrutiny rare cases of thrombosis reported after vaccination, mostly concerning women under 60, which led to the decision to administer the vaccine preferentially to over 60s in Italy, in fact following the same indications provided for Vaxzevria.

But which effectiveness of the Johnson & Johnson vaccine? And what can the most common side effects? Here’s what we know.

Johnson & Johnson’s Janssen vaccine: efficacy

Based on the results of one clinical study involving 44,000 people in the United States, South Africa and Latin American countries, the Janssen vaccine has been shown to be effective in preventing Covid-19 in subjects from 18 years of age.

The study did indeed find one 67% reduction the number of symptomatic cases of Covid-19 after 2 weeks in people who had received the vaccine.

Based on the data collected during this study, Ema and Aifa have so far evaluated the Johnson & Johnson vaccine as effective. up to 77% in the prevention of severe forms Covid-19 after 14 days from administration and up 85% after 28 days (Data: Ministry of Health)

Johnson & Johnson: Side Effects

Following a few rare cases of thrombosis that occurred after the Johnson & Johnson vaccine was administered, there are often potential concerns about adverse events.

However, as reported on the European Medicines Agency website, the most common side effects found in the studies were generally minor O moderate and improved within 1 to 2 days after vaccination.

Specifically, the most common side effects, that is, they strike more than one in 10 people, would be pain at the injection site, headache, fatigue, muscle aches and nausea.

Cough, joint pain, fever, chills, redness and swelling at the injection site occurred instead in less than one in 10 people, while sneezing, tremors, sore throat, rash, sweating, muscle weakness, pain in the arms and legs, back pain, weakness and general feeling of being unwell have interested less than one in 100 people.

They are reported as rare side effects, that is, they strike less than one in 1,000 people, hypersensitivity (allergy) and itchy rash.

As for the danger of thrombosis, or of formation of blood clots in blood vessels in combination with thrombocytopenia (low levels of platelets in the blood) following the administration of the vaccine, it should be borne in mind that it has occurred in less than one in 10,000 people.

In the leaflet made available by Aifa, we read in fact that “following vaccination with COVID-19 Vaccine Janssen Blood clots have been observed very rarely in association with low blood platelet levels. This condition includes severe cases of blood clots even in unusual sites such as the brain, liver, intestines and spleen, in some cases with the presence of bleeding. These cases have occurred in the first three weeks following vaccination and mainly in women under 60 of age”.

Also in the package leaflet are indicated i alarm bells to lend to attention, i symptoms that require prompt medical attention, between these: “severe or persistent headaches, Seizures (seizures), changes in mental status or blurred vision, unusual bruises on the skin somewhere other than the vaccination site, very small round spots located somewhere other than the vaccination site, or shortness of breath, chest pain, leg pain, leg swelling O persistent abdominal pain”.

Furthermore, last May 26, Aifa released a document containing the conclusions reached by the Hemostasis and Thrombosis Working Group, a team of experts in coagulation pathologies appointed to support the Technical Scientific Commission (CTS) following the reporting of thrombotic events related to viral vector vaccine. The document aims to provide doctors and healthcare professionals with the information currently available for identify in a timely manner and then manage appropriately what remains however a very rare adverse event. As for the events observed after the administration of the Janssen vaccine – the document reads – the US surveillance system “Morbidity and mortality weekly report” as of April 30, 2021, reports 17 cases of thrombosis in atypical sites associated with thrombocytopenia on 7.98 million doses of this vaccine administered in North America.


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