Players who display coronavirus symptoms during a Test can be replaced under interim measures introduced by the International Cricket Council.
The world governing body also confirmed that applying saliva to shine the ball will be temporarily banned because of fears of spreading the virus.
Teams found to be in breach could be penalised five penalty runs.
The new regulations will be in place for England's series against West Indies, which begins on 8 July.
Substitute fielders for injured or ill players have always been part of the game, but currently the only way a replacement can bat or bowl is if a player in the original XI suffers a concussion.
Coronavirus replacements will only be permitted in Tests, not one-day or Twenty20 internationals.
Umpires will initially show leniency towards players who apply saliva to the ball during a "period of adjustment" to the regulations.
Subsequently, teams will be warned. After two warnings in an innings, further indiscretions will result in penalty runs being added to the batting side's total.
Players are still permitted to shine the ball using sweat. The ICC's cricket committee last month heard medical advice that suggested it is highly unlikely coronavirus can be transmitted through sweat, but there is an elevated risk through saliva.
The ICC has temporarily lifted the requirement to appoint neutral match officials because of the "logistical challenges" of international travel, meaning English umpires could stand in the series against West Indies.