The FTSE 100 fell on Thursday as the number of COVID-19 cases globally is reported to have exceeded 5 million, according to data from John Hopkins University.
Meanwhile, the UK government remains under pressure to roll out its 'track and trace' strategy following Prime Minister Boris Johnson's commitment to have the contact tracing system in place by the start of June.
At 16:00 the FTSE 100 was 0.8% lower at 6,019.44, while the FTSE 250 was in slight positive territory, up 0.03% at 16,372.51.
EasyJet flew 3.9% higher to 571.4p on the news that the budget airline will resume flights on 15 June on routes with sufficient demand to support profitable flying.
Tate and Lyle was 1.3% ahead to 641.8p on the news that the food and beverage ingredients supplier saw double-digit profit growth in its food and beverage solutions business, up 10% to £162m, in its full-year results for the year ended 31 March 2020 and has maintained its full-year dividend.
Pharmaceutical giant AstraZeneca put on 1% to £88.2 after announcing it would begin first deliveries of the University of Oxford's potential coronavirus vaccine in September 2020, having received $1bn from a US government agency to develop the vaccine.
The company said it had received commitments for at least 400 million doses and secured total manufacturing capacity for one billion doses so far.
Insurer Aviva dipped 0.3% to 238.3p after it reported a fall in its solvency ratio in the first quarter of the year to 182% from 206%, owing to the impact from the pandemic and warned that sales would likely remain below expectations.
Component parts maker Essentra declined 2.7% to 272p on the news that performance took a turn lower in April as the impact from the Covid-19 pandemic deepened, with sales in its components business down by nearly a quarter.
Sabre Insurance, the motor insurance underwriter, fell 2% to 274p following a trading update which revealed that at the end of March its premium was down 5% year on year at £43.7m versus £45.9m, while new business quotations were also lower.
Pets at Home lost 4% to 220.6p after it announced total group revenue exceeded £1bn for the first time in the 52 weeks to 31 March 2020. But it warned that it expects group pre-tax profit in the first half of the financial year 2021 to be 'materially below' the prior year due to COVID-19.
Premier Inn hotel chain owner Whitbread tumbled 12.8% to £24.8 after it reported that while revenue increased 1.1% to £2.1bn in its full-year 2020 results, trading in the period subsequent to the year-end has been adversely impacted by COVID-19.
In the 11-week period to 14 May 2020, total accommodation and F&B revenues were down 75% year-on-year.