Matt Hancock, the UK health secretary, promised 100,000 coronavirus tests a day by the end of April. On the last day of the month, the government claimed to have surpassed that target with 122,000 tests. However, the figure included 40,000 home tests that were posted but have not yet been taken.

On May 3, the number of tests was back down to 76,500. This is short of both the target and the actual testing capacity of the country, but higher than the daily average for most of April.

This situation raises two important questions. First, why has the government not been able to reach the 100,000 tests per day capacity? Second, why is all the testing capacity not being used?

After all, there is no lack of cases. There were over 6,201 new cases recorded on May 1, the UK’s second-highest daily total. Also, the country does not have a shortage of trained workers, equipment or reagents. Here we focus on the four key problems that have limited the level of daily testing in the UK.

1. Taking too long to implement

Part of the reason the UK has had difficulty in meeting the 100,000 tests daily goal was because of its focus on centralised testing centres. In contrast to the robust and wide-reaching testing programmes in Germany and South Korea, the UK government initially decided to centralise all of its laboratory testing in a few large hubs. This should eventually allow for large-scale testing, but it also has taken longer to set up because of logistical complications that using localised testing centres would not have caused.

2. Failure to coordinate the use of resources

The government has also failed to use all the resources available to ramp up its testing capacity. For reasons that are still unclear, the UK recently decided not to buy US-approved saliva test kits that could have eventually supplied the UK with 50,000 test kits a day.

The UK has some of the best laboratories in the world, fully capable of rapid large-scale genetic testing. Yet with the government’s decision to centralise testing, most research laboratories are empty, with trained staff under stay-at-home orders, while care home workers are asked to travel hundreds of miles to be tested. Even the hugely successful NHS coronavirus volunteer pool is reporting that most volunteers have never been called on.

The NHS has been consistently using only a portion of its COVID-19 testing capacity. Even in dedicated testing laboratories, capacity still isn’t filled, with many laboratories closing early due to a lack of swabs to test. And though some report tests running smoothly, stories are emerging of patients having to swab themselves in their cars, lost test samples and results taking over a week to be delivered. As a result, many NHS staff have even been actively discouraged from getting tested.

3. NHS criteria are too restrictive

On May 3, the NHS updated its guidance on who can be tested for COVID-19. Eligible groups now include asymptomatic healthcare workers, NHS patients and care home residents. Symptomatic essential workers, their families and those over 65 can also be tested. Most others are still not eligible for a test unless admitted to a hospital.

There is also a call for the NHS to actively test all non-elective patients spending at least one night in the NHS. These tests can be arranged online and completed at a drive-through testing site.

While this new guidance is a welcome step, most symptomatic patients still can’t be tested and the implementation of the expanded testing has not been smooth. As a result of a lack of clear guidance on who can administer the tests, only 7% of 31,000 tests sent to care homes have been administered. The online system has crashed or closed many times and the actual drive-through testing system has suffered from long delays and unclear guidance. It often requires extensive travel, increasing the burden on those potentially already ill from COVID-19.

4. Delay, delay, delay instead of test, test, test

The UK government’s initial focus on delay tactics resulted in critical delays in implementing testing and contact-tracing programmes, despite the argument that the delay phase would allow test capacity to increase.

While the World Health Organization was telling all countries in March that they needed to “test, test, test” the UK focused on delaying and mitigating the spread of the virus. Other countries continued testing and tracing while implementing physical distancing and lockdowns.

South Korea was able to dramatically reduce its case numbers. In contrast, the UK, despite over a month in lockdown, is still seeing a high daily number of cases and fatalities, suggesting that the absence of robust testing and contact tracing is limiting the effectiveness of lockdown.

The UK’s capacity for testing is clearly increasing and will probably reach 100,000 daily tests in the coming weeks, even without the inclusion of the home test kits sent out on April 30. But with the reopening of the country looming, it is not clear whether these actions will be enough to help stop the spread of the virus.

Prime Minister Boris Johnson recently promised a reopening plan next week, saying that the peak of infection in the UK has now passed. Yet with daily case numbers remaining high and the number of fatalities in the UK on track to overtake even Italy, cautious timing over the next steps is critical.

With a high level of circulating cases of COVID-19, the role of the UK public health system in controlling the outbreak as the country comes out of lockdown will be of utmost importance. Only with a renewed commitment to and coordination of testing, contact tracing and continued physical distancing will the UK be able to keep transmission rates low.