Human rights campaign groups say rapidly changing rules and "chaotic communications" have led to confusion over the fine system nationally, with some people unaware they were breaking the law.
They include 315 fines handed out after April 18 – 404 fewer than the 719 processed in the previous five weeks.
The latest figures cover the easing of restrictions on April 12, which saw the return of outdoor hospitality, non-essential retail and gyms as well as the "rule of six" outdoors.
However, they do not cover the May 17 reopening which saw different households allowed to mix indoors for the first time in months.
Across England and Wales, 120,519 fines were issued by the 43 territorial police forces, British Transport Police and Ministry of Defence for alleged breaches of Covid-19-related laws.
Of those, 5,117 were handed out in the four weeks to May 16, down from 16,699 the month before.
Chairman of the NPCC, Martin Hewitt, said a drop in the number of fines in recent weeks had been expected due to the lifting of restrictions.
But he said police officers would not stop in taking action against rule-breakers across the country.
He added: “For the selfish minority who continue to blatantly break the rules, such as organising or attending illegal indoor gatherings, officers won’t hesitate to take necessary enforcement action."
Of the fines issued in South Yorkshire between March 27 last year and May 16 this year the majority – 2,773 – were recorded under legislation which covers the restriction of movement and large gatherings.
Under other Covid-19-related regulations, there were 42 for failing to wear a face covering when required, and 31 for breaching international travel rules.
There are also 14 fines were given for breaching self-isolation regulations.
The figures, which are updated monthly and cover the whole coronavirus period, could be impacted by fines processed late from previous months, as well as cancellations, the NPCC said.
Human rights campaign group Liberty said "rapidly changing rules, chaotic communications and a misguided emphasis on criminal justice over public health" led to confusion over the fine system and meant interpretation of coronavirus restrictions varied across different police force areas.
Head of policy and campaigns, Sam Grant, said: "At the outset of this pandemic, the Government created sweeping and coercive powers to enforce rules that were communicated chaotically.
"Add to this rapid changes and local lockdowns and policing was inevitably going to be uneven."
People issued with a fine – the maximum is £10,000 – have up to 28 days to pay. Those who cannot pay or wish to contest it can take the matter before the courts.
A spokesperson for the Home Office said police officers have worked "tirelessly" to keep the public safe during the pandemic.
They added: "Whilst the majority of us have been able to stay at home our courageous officers have been out on the streets pursuing cimrinals, protecting the public and enforcing the coronavirus rules where necessary."