Table 1.
Topics related to the COVID-19 vaccine, with metadata on topic name, reading quantity, and date.
| Topic name | Readers (million), n | Date |
| #COVID-19 vaccine could be available in early 2021# | 820 | February 9 |
| #Wei Chen’s Team conducts the Phase I clinical trial of COVID-19 vaccine# | 243.8 | March 20 |
| #When will the COVID-19 vaccine be available# | 50.9 | April 14 |
| #China’s COVID-19 vaccine has entered Phase II clinical trial# | 33 | April 14 |
| #The first participant of the COVID-19 vaccine has not yet shown adverse reactions# | 21 | April 14 |
| #The world’s first COVID-19 inactivated vaccine# | 41.2 | April 19 |
| #What is the COVID-19 inactivated vaccine# | 25.2 | April 21 |
| #Chinese first COVID-19 inactivated vaccine entered Phase II clinical trial# | 4566.4 | April 24 |
| #Phase I clinical trial of the first Chinese COVID-19 vaccine has good results# | 934.5 | May 22 |
| #The safety and effectiveness of the COVID-19 inactivated vaccine have been verified# | 76.9 | May 29 |
| #More than 2000 people received the COVID-19 inactivated vaccine injection# | 479.6 | May 30 |
| #COVID-19 inactivated vaccine is expected to be available at the end of this year or early next year# | 162.1 | May 30 |
| #China developed another kind of COVID-19 inactivated vaccine# | 2000 | June 9 |
| #World’s first COVID-19 inactivated vaccine participant produces antibodies# | 39.4 | June 17 |
| #Chinese COVID-19 vaccine will be launched as early as 2021# | 37.9 | June 18 |
| #CNBG’s COVID-19 inactivated vaccine is not affected by virus mutation# | 1276.2 | June 19 |
| #Chinese three COVID-19 vaccines complete Phase II clinical trials# | 18,000 | June 20 |
| #Domestic COVID-19 inactivated vaccine launches international clinical phase Ⅲ trial# | 84.2 | June 23 |
| #COVID-19 inactivated vaccine production workshop is completed in Wuhan# | 7388.4 | July 2 |
| #WHO requires the protection period of the COVID-19 vaccine to be at least six months# | 56.8 | July 3 |
| #Chinese COVID-19 vaccine Phase 2 clinical trial achieves good results# | 131 | July 21 |
| #COVID-19 vaccine may be available at the end of the year# | 345.4 | July 22 |
| #World first officially releases Phase II clinical data of COVID-19# | 238.3 | July 23 |
| #The price of the COVID-19 vaccine will not exceed $40# | 888.9 | July 29 |
| #Russian COVID-19 vaccine will be free of charge# | 20,000 | August 1 |
| #The first COVID-19 inactivated vaccine workshop passed safety inspection# | 44.9 | August 5 |
| #Beijing COVID-19 inactivated vaccine production workshop can be put into production at any time# | 45.5 | August 5 |
| #Half of the COVID-19 vaccines in Phase III clinical trials come from China# | 150.6 | August 7 |
| #Gates required the COVID-19 vaccine to be priced below $3# | 963.7 | August 8 |
| #Research Institute refutes rumors of COVID-19 vaccine 498 yuan an injection# | 127.4 | August 13 |
| #COVID-19 vaccine not yet be available# | 3 | August 13 |
| #COVID-19 inactivated vaccine two injections less than one thousand yuan# | 3081.6 | August 18 |
| #Domestic COVID-19 inactivated vaccine is expected to be available at the end of December# | 131.6 | August 18 |
| #Russian second COVID-19 vaccine starts Phase 2 clinical trial# | 70.1 | August 18 |
| #COVID-19 vaccine two injections 1000 yuan is too expensive# | 24.2 | August 19 |
| #The price of COVID-19 vaccine can only be based on cost# | 17,000 | August 23 |
| #How to price the COVID-19 vaccine# | 254.2 | August 23 |
| #CNBG declared COVID-19 vaccine is likely to be available at the end of this year# | 354.6 | August 23 |
| #National Health Commission claimed that the price of COVID-19 vaccine was lower than two injections of 1,000 yuan# | 65.9 | August 23 |
| #Domestic COVID-19 inactivated vaccine first appears# | 19,000 | September 5 |
| #Domestic COVID-19 inactivated vaccine appears in CIFTIS# | 5766.4 | September 6 |
| #The COVID-19 vaccine will be priced based on factors such as consumers’ ability to pay# | 134.5 | September 7 |
| #Domestic COVID-19 inactivated vaccine inoculates hundreds of thousands of people with zero infection# | 2102.4 | September 11 |
| #Oxford vaccine volunteers have side effects# | 769.1 | September 9 |
| #The COVID-19 vaccine produced by Pfizer in America has side effects# | 17,000 | September 16 |
| #The COVID-19 inactivated vaccine is expected to be available at the end of the year# | 4319.2 | September 8 |
| #The COVID-19 vaccine price in China will be within the scope of public acceptance# | 11,000 | September 2 |
| #The COVID-19 inactivated vaccine is only one kilometer away from success# | 23,000 | September 2 |
| #Two injections 600 yuan for domestic COVID-19 vaccine # | 7737 | September 3 |
| #The price of domestic COVID-19 vaccine is released# | 4413.4 | September 2 |
| #Four COVID-19 vaccines in China enter Phase III clinical trials# | 428.6 | September 2 |
| #China formally joins COVAX# | 23,000 | October 9 |