Matthew W, a 45-year-old nurse in San Diego, told ABC News San Diego affiliate KGTV that after receiving the vaccine he had only experienced arm soreness as a side-effect of the vaccine.

However, six days later after working a shift in the COVID-19 unit, he said he had chills, muscle pain, and fatigue.

A coronavirus test confirmed him positive for COVID-19, he said.

Following this incident, Dr. Christian Ramers, an infectious disease specialist with the Family Health Centre of San Diego, told KGTV that this was not unexpected.

“We know from the vaccine clinical trials that it is going to take about 10 to 14 days for you to start to develop protection from the vaccine.

“That first dose we think gives you somewhere around 50 percent and you need that second dose to get up to 95 percent,” Ramers further explained.

There is another possibility that the nurse likely contracted COVID-19 before the vaccination but did not rule out the opposite, the expert added.