The Dorset Police officer was spat at by a suspect while walking the beat, and is now 'really struggling' according to a senior officer.
Anna Harvey, chairwoman of the Dorset Police Federation, told BBC News that offenders are 'using Covid as a weapon' and said that the police officer - who is usually fit and healthy - is 'really struggling' with the virus.
Chief Constable James Vaughan said: "Our officers, along with our emergency services colleagues, have remained on the frontline throughout the Covid-19 pandemic, engaging with our communities, protecting the vulnerable and tackling crime.
"It is not acceptable that our officers come into work and face the prospect of being assaulted. For people to be spitting at or biting them is despicable in any circumstances, but particularly in light of the public health emergency we are facing.
"Not only do these assaults put our officers in danger but also their families.
"We will continue to deal swiftly and robustly with any offences of this nature and ensure offenders are brought before the court to face justice.
"We will also do all we can to protect our officers and ensure those who are subjected to these abhorrent attacks are supported within the force."
A spokesperson for Dorset Police said that the officers attended an address in the early morning on 6 January after receiving reports of a man holding up traffic.
The spokesperson said the man was arrested, but then spat at the officer while they were arresting him.
She explained: "He was arrested and during the arrest it was reported that the man spat at an officer.
"A 41-year-old man of no fixed abode has been charged with assault by beating of an emergency worker and being drunk and disorderly in a public place and is due to appear at Poole Magistrates' Court on Tuesday 23rd February 2021."
In April last year, the Director of Public Prosecutions, Max Hill, said that anyone using coronavirus to threaten emergency workers and essential workers would face criminal charges.
He said: "Emergency workers are more essential than ever as society comes together to tackle the coronavirus pandemic.
"I am therefore appalled by reports of police officers and other frontline workers being deliberately coughed at by people claiming to have Covid-19.
"Let me be very clear: this is a crime and needs to stop.
"The CPS stands behind emergency and essential workers and will not hesitate to prosecute anybody who threatens them as they go about their vital duties."