SAN DIEGO (Reuters/ABC News) – A 45-year-old nurse in California, tested positive for the novel coronavirus almost a week after he was vaccinated against the virus. He received a jab of the Pfizer/BioNTech vaccine as the US administration approved it for emergency use.

An Emergency Room (ER) nurse, Mathew W. first disclosed on December 18, through a Facebook post, that he had been vaccinated. Six days after the Christmas Eve he got ill and tested positive for the disease as he worked a shift in COVID-19 unit at a local hospital.

“It’s not unexpected at all. If you work through the numbers, this is exactly what we’d expect to happen if someone was exposed,” said Dr. Christian Ramers, an infectious disease specialist with Family Health Centers of San Diego (as quoted by ABC 10News). Dr. Ramers also served on the clinical advisory panel for the county’s vaccine rollout.

The expert also pointed out that it might be possible that Matthew was infected before receiving the vaccine, as the incubation period may be as much as two weeks. ” This case is a good reminder of why masks, handwashing, and other COVID protocols are important, even after receiving the vaccine,” he said.

Dr. Ramers concluded that to get up to 95% protection against the virus one would need second dose of the vaccine.