News that a fully vaccinated border worker has tested positive for Covid-19 is not unexpected, given no vaccine is 100 per cent protective, an expert says.
On Tuesday, the Ministry of Health announced a border worker at Auckland Airport, who cleans planes, had tested positive for Covid-19 through routine testing, despite having received two doses of the Pfizer vaccine.
University of Otago (Christchurch) infectious diseases expert Professor David Murdoch told Stuff there may still be some people who contract Covid-19, despite receiving a full course of vaccine.
An Auckland Airport worker, who works cleaning planes that have come from countries with a high-risk of Covid-19, has tested positive for the virus, despite being fully vaccinated.
Data on the effectiveness of the Pfizer/BioNTech jab vary between 90 and 95 per cent, or even higher depending on the study, Murdoch said.
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Updated topline results released in April show the Pfizer vaccine is 91.3 per cent effective against Covid-19, seven days through up to six months after the second dose.
The vaccine has also been found to be 100 per cent effective against severe diseases, as defined by the CDC, and 95.3 per cent effective against severe cases of Covid-19 as defined by the FDA.
However, there is still a small proportion of people who may get the virus.
Murdoch said this is fairly typical of vaccines against any disease, as there is no perfect vaccine.
However, effectiveness rates of the Covid-19 vaccines are at the higher end of any vaccine we have.
While it was not necessarily a surprise that a vaccinated person could still contract Covid-19, it was an uncommon event, Murdoch said.
Professor David Murdoch said it is not unexpected a small proportion of fully vaccinated people could still contract Covid-19.
The worker received two doses of the Pfizer/BioNTech vaccine early in the vaccination campaign, in February and March, the Ministry of Health stated.
In the case of Covid-19, those who have still contracted the infection having been vaccinated were much more likely to have a mild form of the virus, or could even be entirely asymptomatic, he said.
Some studies have shown no evidence of serious illness in people who contracted Covid-19 after being fully vaccinated.
Certainly, serious illness and deaths [in Covid-19-positive people who have been vaccinated] are exceedingly rare.
More than 84.2 million people in the United States are fully vaccinated, according to Our World in Data.
The Pfizer vaccine is stated to be about 95 per cent effective, but breakthrough infections happen with all vaccines.
This week, the Centers of Disease Control and Prevention (CDC) in the US advised it had received 5800 reports of breakthrough cases of Covid-19 in people who had been vaccinated.
This makes up just 0.006 per cent of those who are fully vaccinated.
There was also mounting evidence that the vaccine doesn’t just protect against the disease, and prevent serious disease, but that it also prevents transmissibility, Murdoch said.
If a person has had the vaccine, it is much less likely they will be able to transmit the virus if they do get sick.
This is in line with the fact that those without symptoms are much less likely to transmit the virus, he said.
Murdoch said the new case was within what we might expect, and highlighted the value of routine testing among frontline and at-risk workers.
In response to the new case on Tuesday, Prime Minister Jacinda Ardern said officials entirely expect that people who are vaccinated will still get Covid-19.
She said it is still possible to catch Covid-19 if vaccinated, but you are much less likely to get sick.
This is not a worker who is very unwell, she said.
In a statement, the ministry said though we know the Pfizer vaccine is highly effective, at 95 per cent effectiveness a small number may not be protected.
Breakthrough infections happen with all vaccines, it stated.
This shows us how important it is that as many New Zealanders as possible take up the offer to receive the vaccine when they are offered it, and are protected, the ministry said.
The more people that are vaccinated, the more protected we will all be.

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