General view outside GlaxoSmithKline (GSK) headquarters in Brentford, following the outbreak of the coronavirus disease (COVID-19), London, Britain, May 4, 2020. REUTERS/Matthew Childs

General view outside GlaxoSmithKline (GSK) headquarters in Brentford, following the outbreak of the coronavirus disease (COVID-19), London, Britain, May 4, 2020. REUTERS/Matthew Childs

A scientist studies cancer cells inside white blood cells through a microscope at the GlaxoSmithKline (GSK) research centre in Stevenage, Britain November 26, 2019. REUTERS/Peter Nicholls

A scientist prepares stem cells for research at the GlaxoSmithKline (GSK) research centre in Stevenage, Britain November 26, 2019. REUTERS/Peter Nicholls

A scientist prepares stem cells for research at the GlaxoSmithKline (GSK) research centre in Stevenage, Britain November 26, 2019. REUTERS/Peter Nicholls

A scientist prepares stem cells for research at the GlaxoSmithKline (GSK) research centre in Stevenage, Britain November 26, 2019. REUTERS/Peter Nicholls

A scientist prepares stem cells for research at the GlaxoSmithKline (GSK) research centre in Stevenage, Britain November 26, 2019. REUTERS/Peter Nicholls

A scientist uses a molecular weighing robot during research at the GlaxoSmithKline (GSK) research centre in Stevenage, Britain November 26, 2019. REUTERS/Peter Nicholls

A scientist uses a molecular weighing robot during research at the GlaxoSmithKline (GSK) research centre in Stevenage, Britain November 26, 2019. REUTERS/Peter Nicholls

A scientist prepares stem cells for research at the GlaxoSmithKline (GSK) research centre in Stevenage, Britain November 26, 2019. REUTERS/Peter Nicholls

A scientist uses a molecular weighing robot during research at the GlaxoSmithKline (GSK) research centre in Stevenage, Britain November 26, 2019. REUTERS/Peter Nicholls

A scientist uses a molecular weighing robot during research at the GlaxoSmithKline (GSK) research centre in Stevenage, Britain November 26, 2019. REUTERS/Peter Nicholls

A scientist prepares stem cells for research at the GlaxoSmithKline (GSK) research centre in Stevenage, Britain November 26, 2019. REUTERS/Peter Nicholls

Scientists look at test tubes containing stem cells at the GlaxoSmithKline (GSK) research centre in Stevenage, Britain November 26, 2019. REUTERS/Peter Nicholls

A scientist prepares stem cells for research at the GlaxoSmithKline (GSK) research centre in Stevenage, Britain November 26, 2019. REUTERS/Peter Nicholls

Scientists look at test tubes containing stem cells at the GlaxoSmithKline (GSK) research centre in Stevenage, Britain November 26, 2019. REUTERS/Peter Nicholls

A GSK logo is seen on a flag at a GlaxoSmithKline (GSK) research centre in Stevenage, Britain November 26, 2019. REUTERS/Peter Nicholls

A GlaxoSmithKline (GSK) logo is seen at the GSK research centre in Stevenage, Britain November 26, 2019. REUTERS/Peter Nicholls

A GlaxoSmithKline (GSK) logo is seen at the GSK research centre in Stevenage, Britain November 26, 2019. REUTERS/Peter Nicholls

A scientist prepares stem cells for research at the GSK research centre in Stevenage, Britain November 26, 2019. REUTERS/Peter Nicholls

A scientist uses a molecular weighing robot during research at the GSK research centre in Stevenage, Britain November 26, 2019. REUTERS/Peter Nicholls

A scientist prepares stem cells for research at the GSK research centre in Stevenage, Britain November 26, 2019. REUTERS/Peter Nicholls

Brian McNamara, CEO of GSK Consumer Healthcare, poses for a picture at the companyÕs office in London, Britain April 4, 2019. REUTERS/Martinne Geller

Scotland's First Minister Nicola Sturgeon talks with GlaxoSmithKline's (GSK’s) new CEO Emma Walmsley (L) in GSK's new production building in Montrose, Scotland, Britain October 22, 2018. Andy Buchanan/Pool via REUTERS

Scotland's First Minister Nicola Sturgeon talks with GlaxoSmithKline's (GSK’s) new CEO Emma Walmsley (L) in GSK's new production building in Montrose, Scotland, Britain October 22, 2018. Andy Buchanan/Pool via REUTERS

GlaxoSmithKline's (GSK’s) new CEO Emma Walmsley tours GSK's new production building in Montrose, Scotland, Britain October 22, 2018. Andy Buchanan/Pool via REUTERS

Scotland's First Minister Nicola Sturgeon talks with GlaxoSmithKline's (GSK’s) new CEO Emma Walmsley (L) in GSK's new production building in Montrose, Scotland, Britain October 22, 2018. Andy Buchanan/Pool via REUTERS

Scotland's First Minister Nicola Sturgeon talks with GlaxoSmithKline's (GSK’s) new CEO Emma Walmsley (L) in GSK's new production building in Montrose, Scotland, Britain October 22, 2018. Andy Buchanan/Pool via REUTERS

Scotland's First Minister Nicola Sturgeon talks with GlaxoSmithKline's (GSK’s) new CEO Emma Walmsley (L) in GSK's new production building in Montrose, Scotland, Britain October 22, 2018. Andy Buchanan/Pool via REUTERS

A general view of GlaxoSmithKline (GSK) Asia House is seen in Singapore, March 21, 2018. Picture taken March 21, 2018. REUTERS/Loriene Perera

A SMRT train travels past GlaxoSmithKline (GSK) Asia House in Singapore, March 21, 2018. Picture taken March 21, 2018. REUTERS/Loriene Perera

The GlaxoSmithKline (GSK) logo is seen on top of GSK Asia House in Singapore, March 21, 2018. Picture taken March 21, 2018. REUTERS/Loriene Perera

The GlaxoSmithKline (GSK) logo is seen on top of GSK Asia House in Singapore, March 21, 2018. Picture taken March 21, 2018. REUTERS/Loriene Perera

An aerial view of GlaxoSmithKline (GSK) Asia House is seen in Singapore, March 21, 2018. Picture taken March 21, 2018. REUTERS/Loriene Perera

A SMRT train travels past GlaxoSmithKline (GSK) Asia House in Singapore, March 21, 2018. Picture taken March 21, 2018. REUTERS/Loriene Perera

The GlaxoSmithKline (GSK) logo on top of GSK Asia House is seen through vertical louvres in Singapore, March 21, 2018. Picture taken March 21, 2018. REUTERS/Loriene Perera

The GlaxoSmithKline (GSK) logo is seen on top of GSK Asia House in Singapore, March 21, 2018. Picture taken March 21, 2018. REUTERS/Loriene Perera

An exterior view of GlaxoSmithKline (GSK) Asia House is seen in Singapore, March 21, 2018. Picture taken March 21, 2018. REUTERS/Loriene Perera

An aerial view of GlaxoSmithKline (GSK) Asia House is seen in Singapore, March 21, 2018. Picture taken March 21, 2018. REUTERS/Loriene Perera

GlaxoSmithKline (GSK) CEO, Emma Walmsley, arrives for a meeting in Downing Street in central London, Britain, October 9, 2017. Picture taken October 9, 2017. REUTERS/Toby Melville

GlaxoSmithKline (GSK) CEO, Emma Walmsley, and Vodafone CEO Vittorio Colao, arrive for a meeting in Downing Street in central London, Britain October 9, 2017. REUTERS/Toby Melville

GlaxoSmithKline (GSK) CEO, Emma Walmsley, carries documents as she arrives for a meeting in Downing Street in central London, Britain October 9, 2017. REUTERS/Toby Melville

GlaxoSmithKline (GSK) CEO, Emma Walmsley, arrives for a meeting in Downing Street in central London, Britain October 9, 2017. REUTERS/Toby Melville

A GlaxoSmithKline logo is seen outside one of its buildings in west London, February 6, 2008. REUTERS/Toby Melville/File Photo

The GlaxoSmithKline building is pictured in Hounslow, west London June 18, 2013. REUTERS/Luke MacGregor/File Photo

A GlaxoSmithKline logo is seen outside one of its buildings in west London, February 6, 2008. REUTERS/Toby Melville/File Photo

The GlaxoSmithKline building is pictured in Hounslow, west London June 18, 2013. REUTERS/Luke MacGregor/File Photo RTX11R3W GLOBAL BUSINESS WEEK AHEAD PACKAGE - SEARCH "BUSINESS WEEK AHEAD JULY 25" FOR ALL IMAGES

GlaxoSmithKline’s top-selling lung drug Advair is now facing generic competition after the drug lost patent protection.

The GlaxoSmithKline building is pictured in Hounslow, west London, Britain, June 18, 2013. REUTERS/Luke MacGregor/File Photo

Andrew Witty, CEO of GlaxoSmithKline, speaks at the Milken Institute Global Conference in Beverly Hills, California, U.S., May 2, 2016. REUTERS/Lucy Nicholson

The GlaxoSmithKline building is pictured in Hounslow, west London June 18, 2013. REUTERS/Luke MacGregor/File Photo

The GlaxoSmithKline building is pictured in Hounslow, west London June 18, 2013. REUTERS/Luke MacGregor/File Photo

Signage for GlaxoSmithKline is seen on it's offices in London, Britain, March 30, 2016. REUTERS/Toby Melville/File Photo GLOBAL BUSINESS WEEK AHEAD PACKAGE - SEARCH 'BUSINESS WEEK AHEAD APRIL 25' FOR ALL IMAGES

The GlaxoSmithKline building is pictured in Hounslow, west London, Britain, in this June 18, 2013 file photo. REUTERS/Luke MacGregor/Files

GSK-CHINA/ - Chart showing slowed growth of multinational corporations in China's pharmaceutical market. (SIN03)

Herve Gisserot, general manager for GSK China, poses for a photograph in front of a company logo during an interview with Reuters at an office in Shanghai, China, November 25, 2015. GlaxoSmithKline Plc has cut 40 percent of its sales reps in China and axed some units as it eyes a return to growth in 2016, after sales plunged during a bribery scandal that landed it with a record $490 million fine in 2014. Picture taken November 25. To match Interview GSK-CHINA/ REUTERS/Ben Hirschler

GSK-MALARIA/VACCINE - Map of countries with ongoing transmission ofMalaria, includes charts showing number of cases and deaths. (SIN03)

Britain's Catherine, Duchess of Cambridge speaks with wheelchair athlete Sheikh Sheikh during her visit to a SportsAid workshop at the GlaxoSmithKline (GSK) Human Performance Laboratory in west London November 12, 2014. REUTERS/David Parker/pool (BRITAIN - Tags: ROYALS SPORT HEALTH)

Britain's Catherine, Duchess of Cambridge attends a SportsAid workshop at the GlaxoSmithKline (GSK) Human Performance Laboratory in west London November 12, 2014. REUTERS/David Parker/pool (BRITAIN - Tags: ROYALS SPORT HEALTH)

Britain's Catherine, Duchess of Cambridge (L) speaks with young athlete Emma Allen during her visit to a SportsAid workshop at the GlaxoSmithKline (GSK) Human Performance Laboratory in west London November 12, 2014. REUTERS/David Parker/pool (BRITAIN - Tags: ROYALS SPORT HEALTH)