Everyone around the world is happy and excited that there’s finally a vaccine that works against COVID-19.

What's not to like about something that can keep us alive right?

But as always, there’s a catch here.

A nurse in California has tested positive for the virus about a week after receiving Pfizer Inc's vaccine. Reuters, quoting a report from ABC News reported that Matthew W., 45, became sick six days after he received the vaccine.

The nurse was said to have suffered from chills, muscle aches and fatigue.

Upon testing, he found himself positive for the virus.

Vaccine needs time to work

However, the same report quoted an infectious disease specialist with Family Health Centers of San Diego, Christian Ramers, as saying that the vaccine takes about 10 to 14 days for a human to start developing protection from it.

"That first dose we think gives you somewhere around 50%, and you need that second dose to get up to 95%," he was quoted as saying.